C语言练习题【1】

#define M 10
#include<math.h>
#include<stdio.h>
#include<string.h>    
int main1234(){
    #if( 0 )
    double x,s;
    printf("input number:\n");
    scanf("%lf",&x);
    s=sin(x);
    printf("sine of %lf is %lf\n",x,s);

    char s[80],c='a';
    int i=0;
    //scanf("%s",s); //gets可以读入空格，遇到回车才会停止；而scanf遇到空格、回车和Tab键都会认为输入结束
    gets(s);
    while(s[i]!='\0')
    {if(s[i]==c) s[i]=s[i]-32;
     else if(s[i]==c-32) s[i]=s[i]+32;
    i++;}
    puts(s);    //ahAMa 
    
    #endif //输入输出

    #if( 0 ) 
     printf("12345678901234567890\n");
    printf("\\abc\n\'abd\bc\"\n");
    printf("erg\r");
    printf("\110\x49\tijk\n");
    #endif //转义字符 字符串的输出


    #if( 0 )
    int a,b=32;
    float x,y=8.88;
    char cl='k',c2;
    a=y;
    x=b;
    a=cl;
    c2=b;
    printf("%d,%f,%d,%c",a,x,a,c2);
    #endif //类型转化

    #if( 0 )
    //int i=8;
    //printf("%d\n",++i);
    //printf("%d\n",--i);
    //printf("%d\n",i++);
    //printf("%d\n",i--);
    //printf("%d\n",-i++);
    //printf("%d\n",-i--);
    //???
    //int i=5,j=5,p,q;
    //p=(i++)+(i++)+(i++);
    //q=(++j)+(++j)+(++j);
    //printf("%d,%d,%d,%d",p,q,i,j);
    #endif//自增自减运算

    #if( 0 )
    //char a='B',b='o',c='k';
    //putchar(a);putchar(b);putchar(b);putchar(c);putchar('\t');
    //putchar(a);putchar(b);
    //putchar('\n');
    //putchar(b);putchar(c);
    #endif //使用putchar 输出字符

    #if( 0 )
    //int a=15;
    //float b=123.1234567;
    //double c=12345678.1234567;
    //char d='p';
    //printf("a=%d,%5d,%o,%x\n",a,a,a,a);
    //printf("b=%f,%lf,%5.14f,%e\n",b,b,b,b);
    //printf("c=%lf,%f,%8.41lf\n",c,c,c);
    //printf("d=%c,%8c\n",d,d);
    #endif //格式输出

    #if( 0 )
    //int i=8;
    //printf("%d\n",++i);
    //printf("%d\n",--i);
    //printf("%d\n",i++);
    //printf("%d\n",i--);
    //printf("%d\n",i++);
    //printf("%d\n",i--);
    //int i=8;
    //printf("%d\n%d\n%d\n%d\n%d\n%d\n",++i,--i,i++,i--,i++,i--);
    #endif //格式输出

    #if( 0 )
    char str[30];
    char ch;
    printf("请输入字符串：");
    //gets(str); //可接受回车键之前输入的所有字符，并用’\0’替代 ‘\n’.回车键不会留在输入缓冲区中
    scanf("%s",&str);//当遇到回车，空格和tab键会自动在字符串后面添加’\0’，但是回车，空格和tab键仍会留在输入的缓冲区中。
    //printf("%s",str);
    puts(str); //输出字符串时会将’\0’自动转换成’\n’进行输出  
    getchar();  //接受缓冲区的回车
    ch = getchar();  //接受用户输入的一个字符
    //scanf("%c",&ch);
    printf("ch = %c\n",ch);
    #endif  //gets puts getchar() 的用法

    #if( 0 )
    int a;
    printf("input a number\n");
    scanf("%d",&a);
    printf("%ld\n",a);

    long a;
    printf("input a long integer");
    scanf("%ld\n",&a);
    printf("%ld\n",a);

    char a,b,c;
    printf("input char a,b,c\n");
    scanf("%c %c %c",&a,&b,&c);
    printf("%d,%d,%d\n%c,%c,%c\n",a,b,c,a-32,b-32,c-32);

    char ch;
    ch=getchar();
    putchar(ch-32);
    putchar('\n');

    int num;
    scanf("%x",&num);
    printf("%d",num);
    #endif //格式的输入与输出

    #if( 0 )
    int a=1;
    a=(int)((double)(3/2)+0.5+(int)1.99*2);
    printf("%d\n",a);
    #endif //优先级运算

    #if( 0 )
    char c='k';
    int i=1,j=2,k=3;
    float x=3e+5,y=0.85;
    printf("%d,%d\n",!x*!y,!!!x);
    printf("%d,%d\n",x||i&&j-3,i<j&&x<y);
    printf("%d,%d\n",i==5&&c&&(j=8),x+y||i+j+k);
    #endif //逻辑符的使用

    #if( 0 )
    int a,b,c,temp;
    printf("请输入三个数\n");
    scanf("%d%d%d",&a,&b,&c);
    if( a > b )
    {
        temp = a;
        a = b;
        b = temp;
    }
    if( a > c )
    {
        temp = a;
        a = c;
        c = temp;
    }
    if( b > c )
    {
        temp = b;
        b = c;
        c = temp;
    }
    printf("%d %d %d\n" , a,b,c);
    #endif //从大到小排列

    #if( 0 )
    char c1;
    printf("请输入一个字符\n");
    scanf("%c",&c1);
    //if(c1  >= 'A'&& c1 <= 'Z')
    //{
    //    c1+=32;
    //    printf("%c %d\n",c1,c1);
    //}
    //else if (c1  >= 'a'&& c1 <= 'z')
    //{
    //    c1-=32;
    //    printf("%c %d\n",c1,c1);
    //}
    //else
    //{
    //    printf("%c %d\n",c1,c1);
    //}
    c1=(c1  >= 'A'&& c1 <= 'Z') ? c1+32 : (c1  >= 'a'&& c1 <= 'z') ? c1-32 : c1;
    printf("%c %d\n",c1,c1);
    #endif //转换大小写

    #if( 0 )
    int i,j,k;
    for (i = 1; i < 5; i++)
    {
        for (j = 1; j < 5; j++)
        {
            for (k = 1; k < 5; k++)
            {
                if(i!=j&&i!=k&&j!=k)
                {
                    printf("%d,%d,%d\n",i,j,k);

                }
            }
        }
    }
    #endif  //1,2,3,4个数字组成互不相同且无重复数字的三位数

    #if( 0 )
    //方法①
    //int s=1;
    //double i,pi=0;   //pi=0一定要赋值
    //for (i = 1; fabs(s/i) >1e-6;)   //fabs()函数求浮点数的绝对值 需要引用头文件#include<math.h>
    //{
    //    pi+=s/i;
    //    i=i+2;
    //    s=-s;
    //}
    //pi*=4;
    //printf("pi=%g\n",pi);

    //方法②
    //double i,pi=0,s=1;   //pi=0一定要赋值
    //for (i = 1; fabs(pow(-1,s+1)/i) >1e-6;)   //fabs()函数求浮点数的绝对值 pow(x,y) 表示x的y次方 需要引用头文件#include<math.h> 
    //{
    //    pi+=pow(-1,s+1)/i;
    //    i=i+2;
    //    s++;
    //}
    //pi*=4;
    //printf("pi=%g\n",pi);

    //方法③
    //int s=1; double n=1.0,t=1,pi=0;
    //while (fabs(t)>1e-6)   //绝对值小于10^-6为止 所以大于10^-6进行循环
    //{
    //    pi=pi+t; 
    //    n=n+2;
    //    s=-s;
    //    t=s/n;
    //}
    //pi=pi*4;
    //printf("pi=%10.6lf\n",pi);
    #endif //用π/4≈1-1/3+1/5-1/7+...公式求π的近似值直到某一项的绝对值小于10^-6为止 

    #if( 0 )
    //①my method
    //long a=1,b=1,i;
    //printf("%d\n%d\n",a,b);
    //for (i = 1; i <= 19; i++)  //两个数循环19次 一共输出38个数
    //{
    //    a=a+b;
    //    b=a+b;
    //    printf("%d\n%d\n",a,b);
    //}

    //②reference
    //long f1,f2;
    //int i;
    //f1=1; f2=1;
    //for (i = 1; i <=20; i++)
    //{
    //    printf("%12ld %12ld",f1,f2);
    //    if(i%2==0)
    //    {
    //        printf("\n");
    //    }
    //    f1=f1+f2;
    //    f2=f2+f1;
    //}
    #endif //求斐波拉列数列前40个数。斐波拉列数特点  (n=1)时 F(1)=1  (n=2)时 F(2)=1  (n>=3)时 F(n)=F(n-1)+F(n-2) 

    #if( 0 )
    long a[20] = {1,1};
    int i;
    for ( i = 0; i < 20; i++)
    {
        if(i>=2)
        {
            a[i] = a[i-1] + a[i-2];
        }
        if(i % 5 == 0)
        {
            printf("\n");
        }
        printf("%12d",a[i]);
    }
    printf("\n");
    #endif //用数组求斐波拉列数列前20个数

    #if ( 0 )
    int m , n ,temp, i;
    printf("input m and n");
    scanf("%d %d",&m,&n);
    if( m < ng )
    {
        temp = m;
        m = n;
        n = temp;
    }
    //for (i = m ; i > 0 ;i++)  //从大数开始寻找满足条件的自然数
    //{
    //    if(i % m== 0 && i % n == 0  )
    //    {
    //        printf("%d and %d LVW is %d",m,n,i);
    //        break;
    //    }
    //}
    for ( i = n; i > 0; i--)    //从大到小寻找满足条件的自然数
    {
        if( m % i == 0 && n % i == 0 )
        {
            printf("%d and %d GCD is %d",m,n,i);
            break;
        }
    }
    #endif    //求最小公倍数和最大公约数

    #if( 0 )
    int a[10];
    int i,j,temp;
    for (i = 0; i < 10; i++)
    {
        scanf_s("%d",&a[i]);
    }
    //外层控制循环多少趟，内层控制每一趟的循环次数
    for (j = 0; j < 9; j++)    //N个数字要排序完成 总共进行N-1趟排序 
    {
        bool flag = false;   //假如没有元素交换
        for (i = 0; i < 10-j-1; i++)  //每i趟的排序次数为(N-i)// -1防止a[i+1]越界
        {
                if(a[i] > a[i+1])
                {
                    temp = a[i+1];
                    a[i+1] = a[i];
                    a[i] = temp;
                    flag = true;
                }
        }
        if(!flag)   //说明数组已经有序不需要再进行比较
        {
            break;
        }
    }
    for (i = 0; i < 10; i++)
    {
        printf("%5d\n",a[i]);
    }
    #endif    //冒泡排序

    #if( 0 )
    int i, j ,k = 0 , temp,  a[10];
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",&a[i]);
    }
    for ( i = 0; i < 9; i++)
    {
        k = i ;
        for ( j = i + 1; j < 10; j++)
        {
            if(a[k] < a[j] )
            {
                    k = j ;
                    temp = a[i];
                    a[i] = a[k];
                    a[k] = temp;
            }
        }
    }
        for (j = 0; j < 10; j++)
    {
        printf("%5d\n",a[j]);
    }
    #endif    //选择排序

    #if( 0 )
    int a[2][3];
    int i,j,k,b[6];
    int temp;
    int y,z;    //一维数组转换成二维数组时候用到的
    k = 0;        //初始化k的值
    
    //输入二维数组每个元素的值
    for ( i = 0; i < 2; i++)
    {
        for ( j = 0; j < 3; j++)
        {
            scanf("%d",&a[i][j]);
        }
    }

    //转换一维数组
    for ( i = 0; i < 2; i++)
    {
        for ( j = 0; j < 3; j++)
        {
            //b[k] = a[i][j];
            //k++;
            b[i*3+j] = a[i][j];
        }
    }

    //对一维数组b[6]进行冒泡排序
    for ( j = 0; j < 5; j++)
    {
        for ( i = 0; i < 5-j; i++)
        {
            if(b[i]>b[i+1])
            {
                temp = b[i];
                b[i] = b[i+1];
                b[i+1] = temp;
            }
        }
    }

    //再将排好序的一维数组b[6]转换成二维数组a[2][3]
    //重新定义一个变量y z ，是为了避免变量之间的冲突
    for ( y = 0; y < 2; y++)
    {
        for ( z = 0; z < 3; z++)
        {
            a[y][z] = b[y*3+z];        //一维数组转换为二维数组
        }
    }

    //输出 
    for ( i = 0; i < 2; i++)
    {
        for ( j = 0; j < 3 ; j++)
        {
            printf("%3d",a[i][j]);
        }
    }
    #endif    //二维数组的冒泡排序

    #if( 0 )
    // 用变量存储累加的结果
    //int a[5][3] = {{80,75,92},{61,65,71},{59,63,70},{85,87,90},{76,77,85}};
    //int i, j;
    //double math = 0 , c = 0 , foxpro = 0;
    //for ( i = 0; i < 3; i++)
    //{
    //    for ( j = 0; j < 5; j++)
    //    {
    //        if(i==0)
    //        {
    //            math+=a[j][i];
    //        }
    //        if(i==1)
    //        {
    //            c+=a[j][i];
    //        }
    //        if(i==2)
    //        {
    //            foxpro+=a[j][i];
    //        }
    //    }
    //}
    //math /= 5.0; c /= 5.0; foxpro /= 5.0;
    //printf("math: %lf c: %lf foxpro: %lf  and sum: %lf",math,c,foxpro,(math+c+foxpro)/3.0);

    // 用一维数组存累加的结果（Preferable）
    int a[5][3] = {{80,75,92},{61,65,71},{59,63,70},{85,87,90},{76,77,85}};
    int i, j;
    double average, sum = 0, v[3];
    for ( i = 0; i < 3; i++)
    {
        for ( j = 0; j < 5; j++)
        {
            sum += a[j][i];
        }
        v[i] = sum / 5.0;  //将每一科的平均成绩存到一维数组里
        sum = 0;
    }
    average = ( v[0] +v[1] + v[2]) / 3.0; 
    printf("math: %lf c: %lf foxpro: %lf  and sum: %lf",v[0],v[1],v[2],average);
    #endif //二维数组求平均成绩

    #if( 0 )
    int a[2][3]={{5,2,0},{1,3,8}}, i, j;
    for ( i = 0; i < 2; i++)
    {
        
        for ( j = 0; j < 3; j++)
        {
            printf("%3d",a[i][j]);
        
        }
        printf("\n");
    }
    printf("\n");
    for ( i = 0; i < 3; i++)
    {
        
        for ( j = 0; j < 2; j++)
        {
            printf("%3d",a[j][i]);
        
        }
            printf("\n");
    }
    #endif //将二维数组的行和列元素互换，存到另外一个二维数组里

    #if( 0 )
    int i ,j,a[3][3];
    for ( i = 0; i < 3; i++)
    {
        for ( j = 0; j < 3; j++)
        {
            printf("a[%d][%d]=",i,j);
            scanf_s("%d",&a[i][j]);
        } 
    }
    for ( i = 0; i < 3; i++)
    {
        for ( j = 0; j < 3; j++)
        {
            if( i == 1 || j == 1)
                printf("%-6d",a[i][j]);
            else
                printf("%-6c",' ');
        } 
            printf("\n");
    }
    #endif //按照九宫格的形式，输入三行，按数组原来位置输出第一行和第一列的所有元素
    
    #if( 0 )
    int i, j,temp, row=0, column=0;
    int a[3][4] = {{12,20,31,4},{5,16,27,8},{9,10,11,12}};
    int max = a[0][0];
    for ( i = 0; i < 3; i++)
    {
        for ( j = 0; j < 4; j++)
        {
            if( a[i][j] > max )
            {
                //temp = max;
                max = a[i][j];
                //a[i][j] = temp;
                row = i;
                column = j;
            }
        }
    }
    printf("row: %2d , column：%2d  max: %2d",row,column,max);
    #endif //找出数组中最大值并且指出它的行号和列号

    #if( 0 )
    static int a[M] = {-12,0,6,16,23,56,80,100,110,115};
    int n,low,mid,high,found;
    low = 0;
    high = M-1;
    found = 0;
    printf("Input a number to be searched\n");
    scanf("%d",&n);
        while(low <= high)
        {
        mid = (low + high) / 2;
        if(n == a[mid])
        {
            found = 1;
            break;
        }
        else if(n > a[mid])
            low = mid + 1;
        else
            high = mid-1;
        }
    
    if(found == 1)
        printf("The index of %d is %d",n,mid);
    else
        printf("There is not %d",n);
    #endif //二分法

    #if( 0 )
    int power(int a, int b);
    int x,y,z;
    scanf("%d %d",&x,&y);
    z=power(x,y);
    printf("%d\n",z);
    #endif  //实现pow()函数

    #if( 0 )
    int result;
    int square(int x);
    int factorical(int y);
    result = factorical(square(2))+factorical(square(3));
    printf("计算结果：%d",result);
    #endif  //自定义平方函数 阶乘函数

    #if( 0 )
    int result;
    int factorical2(int n);
    int num ;
    scanf("%d",&num);
    result = factorical2(num);
    printf("计算结果：%d\n",result);
    #endif  //输一个数求它的阶乘

    #if( 0 )
    void hanoi(int n , char x , char y , char z );
    int n;
    scanf("%d",&n);
    hanoi(n , 'X' , 'Y', 'Z');
    #endif  //汉诺塔

    #if( 0 )
    void average(int grade[]);
    int score[10] = {10,20,30,40,50,60,70,80,90,100};
     average(score);

    #endif  //写一个average函数求平均成绩

    #if( 0 )
    int i;
    int fac(int a);
    for ( i = 1; i <=5 ; i++)
    {
        printf("%d!=%d\n",i,fac(i));
    }
    #endif //使用静态变量求阶乘

    #if( 0 )
    //char string[50],char1; 
    //void removestr(char str[],char char2);
    //puts("请输入一个字符串");
    //gets(string);
    //printf("您输入的字符串是：%s\n",string);
    //printf("请输入一个要删除的字符\n");
    //char1=getchar();
    //removestr(string,char1);

    extern void enter_string(char str[]);
    extern void delete_string(char str[],char ch);
    extern void print_string(char str[]);
    //以上声明是在本函数中将要调用的在其他文件中定义的函数

    char string[50], char1;
    enter_string(string);
    puts("请输入一个要删除的字符");
    char1=getchar();
    delete_string(string,char1);
    print_string(string);

    #endif // 输入一个字符 在字符串中删除对应的字符 使用外部函数

    #if( 0 )
    int a[10] = {9,8,7,6,5,4,3,2,1,0};
    int *p, i;
    //for ( i = 0; i < 10; i++)
    //{
    //    printf("%d",*(a + i));
    //}
    for (p = a; p < (a+10); p++)  //数组名a表示数组第一个元素的地址 即 p = &a[0]
    {
        printf("%d", *p);
    }
    /****************************************************/
    int *p, i , a[10];
    p = a;
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",p++ );
    }
    p = a;
    for ( i = 0; i < 10; i++)
    {
        printf("%d",*p++);
    #endif   //用指针遍历数组

    #if( 0 )
    int a[10] = {1,2,3,4,5,6,7,8,9,10},
    *p = &a[3], b;
    b = p[5];
    printf("%d",b);
    #endif  //一维数组指针取址

    #if( 0 )
    int a[3], *p, *s;
    for (p = a; p < a+3; p++)
    {
        scanf("%d",p);
    }
    for (p = a, s = a; p < a+3; p++)
    {
        if(*p>*s) s = p;
    }
    printf("%d",s - a );
    #endif  //一维数组借助指针变量求最大值及所在位置

    #if( 0 )
      int x[] = {10,20,30};
      int *px = x;
      printf("%3d", ++*px);    printf("%3d", *px);
      //px = x;
      printf("%3d", (*px)++);printf("%3d", *px);
      //px = x;
      printf("%3d", *px++);    printf("%3d", *px);
      //px = x;
      printf("%3d", *++px);    printf("%3d\n", *px);
    #endif  //一维数组输出 *px++ , (*px)++ , *++px

    #if( 0 )
    int a[3][4] = {{0,1,2,3},{4,5,6,7},{8,9,10,11}};
    printf("a: %d\n",a);
    printf("*a: %d\n",*a);
    printf("a[0]: %d\n",a[0]);
    printf("&a[0]: %d\n",&a[0]);
    printf("&a[0][0]: %d\n",&a[0][0]);
    #endif    //输出二维数组的地址

    #if( 0 )
    //int a[10] = {3,7,9,11,0,6,7,5,4,2}, b[10];
    //int *p1 = a , *p2, i ,j;
    //for (i = 9, j=0; i >= 0; i--,j++)
    //{
    //      b[j] = *(p1 + i);
    //}
    //for ( j = 0; j < 10; j++)
    //{
    //    printf("%4d",b[j]);
    //}
    /*************************************************************/

    //int a[10] = {3,7,9,11,0,6,7,5,4,2};
    //int i;
    //void reverse(int x[],int n);
    //for ( i = 0; i < 10; i++)
    //{
    //    printf("%4d",a[i]);
    //}
    //printf("\n");
    //printf("反序为：\n");
    //reverse(a,10);
    //for ( i = 0; i < 10; i++)
    //{
    //    printf("%4d",a[i]);
    //}
    //printf("\n");
    /*************************************************************/

    int a[10] = {3,7,9,11,0,6,7,5,4,2};
    int i;
    void reverse1(int *x,int n);
    for ( i = 0; i < 10; i++)
    {
        printf("%4d",a[i]);
    }
    printf("\n");
    printf("反序为：\n");
    reverse1(a,10);
    for ( i = 0; i < 10; i++)
    {
        printf("%4d",*(a+i));
    }
    printf("\n");
    #endif  //将数组a中n个整数按相反顺序存放

    #if( 0 )
    //int a[10],i;
    //void sort(int a[], int n);
    //for ( i = 0; i < 10; i++)
    //{
    //    scanf("%d",&a[i]);
    //}
    //sort(a,10);
    //for ( i = 0; i < 10; i++)
    //{
    //    printf("%2d",a[i]);
    //    printf("\n");
    //}

    int a[10],i;
    void sort1(int *a, int n);
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",&a[i]);
    }
    sort1(a,10);
    for ( i = 0; i < 10; i++)
    {
        printf("%2d",a[i]);
        printf("\n");
    }
    #endif  //从大到小排列数组的10个数

    #if( 0 )
    int a[3][4] = {{0,1,2,3},{4,5,6,7},{8,9,10,11}};
    int (*p)[4]; //声明二维数组指针变量    (一行存4个元素地址的一维数组)    “4”表示二维数组分解为多个一维数组的长度  “int *p[4]指针数组：这个数组大小为4，它的元素均为指针类型数据，称为指针数组”
    int i,j;    //定义行和列
    p = a;        //二维数组的地址指向了数组指针的地址
    for ( i = 0; i < 3; i++)
    {
        for ( i = 0; i < 4; i++)
        {
            printf("%2d",*(*(p+i)+j)); // p+i：是行的地址 a[i]; *(p+i)：是列的首地址 &a[i][0]; *(p+i)+j：是列的首地址+列的位置(二维数组i行j列的元素地址);  *(*(p+i)+j)：是行和列二维数组的值;
        }
    }
    #endif  //遍历二维数组(行指针)

    #if( 0 )
    int a[3][4]={{1,2,3,4},{5,6,7,8},{9,10,11,12}};
    int (*p)[4];  //表示定义一个指针变量，它指向一个包含12个整型元素的一堆数组
    int i=0;
    p=a;
    printf("%d\n",(*p)[11]);    // 最后一个元素的值
    #endif    //数组指针变量


    #if( 0 )
    //char string[] = "I love you";
    //puts(string);

    //char *string = "I love you";
    //printf("%s",string);

    //下标法
    //char string[] = "I love you", b[50];
    //int i;
    //for ( i = 0; *(string+i)!='\0'; i++)
    //{
    //     *(b+i) = *(string+i);
    //}
    //*(b + i) = '\0';
    //for ( i = 0; b[i] != '\0'; i++)
    //{
    //    printf("%c",b[i]);
    //}

    //指针方法
    char string[] = "I love you", b[50], *p1 , *p2;
    int i;
    p1 = string;
    p2 = b;
    for ( ; *p1 != '\0'; p1++, p2++)
    {
        *p2 = *p1;
    }
    *p2 =  '\0';
    printf("%s\n",string);
    for ( i = 0; b[i] != '\0' ; i++)
    {
        printf("%c",b[i]);
    }
    #endif     //输出字符串

    #if( 0 )
    //指针方法
    //void copy(char a[],char b[]);
    //char str1[] = "Duck don't do it";
    //char str2[] = "You're thinking peach";
    //printf("str1：%s \n str2：%s \n",str1,str2);
    //printf("copy string str1 to string str2:\n");
    //copy(str1,str2);
    //printf("\nstr1：%s \n str2：%s\n",str1,str2);

    //下标法
    void copy1(char *a,char *b);
    char *str1 = "you are a pig";
    char str2[] = "yes,you too";
    printf("str1：%s \n str2：%s \n",str1,str2);
    printf("copy string str1 to string str2:\n");
    copy1(str1,str2);
    printf("str1：%s \n str2：%s",str1,str2);
    #endif     //复制字符串

    #if( 0 )
    int max(int ,int );      //声明一个求最大值的函数
    int(*p)(int , int );  //声明指向函数max的指针变量p
    int a,b,c;
    p = max;              //将函数名max赋值给指针变量p,使p指向函数max
    scanf("%d %d",&a,&b);
    c = (*p)(a,b);          //通过指向函数max的指针变量p调用函数max
    printf("a = %d, b = %d, max = %d \n", a ,b ,c);
    #endif    //用函数指针求最大值

    #if( 0 )
    char *day[ ] = {"Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"};
    int today;
    printf("今天是星期");
    scanf("%d", &today);
    //char **today = day;
    //int i;
    //for ( i = 0; i < 7; i++)
    //{
    //    printf("%s",*(day + i));
    //}
    switch (today)
    {
    case 1:
        printf("%s",*day);
        break;
    case 2:
        printf("%s",*(day+1));
        break;
    case 3:
        printf("%s",*(day+2));
        break;
    case 4:
        printf("%s",*(day+3));
        break;
    case 5:
        printf("%s",*(day+4));
        break;
    case 6:
        printf("%s",*(day+5));
        break;
    case 7:
        printf("%s",*(day+6));
        break;
    }
    #endif  //指针数组输出星期几

    #if( 0 )
    double area (double x1, double y1);
    double length (double x2, double y2);
    double cal(double x3, double y3, double (*p)(double , double ));
    double x,y,S = 0, L = 0;
    printf("please input two sides \n");
    scanf("%lf %lf",&x,&y);
    S = cal(x, y, area);
    L = cal(x, y, length);
    printf("S = %.2lf\n", S);
    printf("L = %.2lf",L);
    #endif    //调用同一个函数，第一次求三角形的面积，第二次求三角形的第三边长

    #if( 0 )
    int max(int, int);
    int min(int, int);
    int add(int, int);
    void process(int x,int y,int (*fun)(int,int) );

    int a,b;
    printf("import a and b \n");
    scanf("%d %d",&a,&b);

    printf("max = ");
    process(a , b , max);

    printf("\nmin = ");
    process(a , b , min);

    printf("\nadd = \n");
    process(a , b , add);
    #endif    //使用函数指针实现多态的功能（求最大值、最小值、之和）

    #if( 0 )
    //double sorce[][4] = {{60.0,70.0,80.5,90.5},{56.0,89.0,67.0,88.0},{34.2,70.5,90.5,89.0},{95.0,68.0,78.5,88.0}};
    //double *search(double(*pointer)[4], int n);//声明一个指针函数  第一个形参是 数组指针(一行存4个元素地址的一维数组)   第二个形参是输入的学生序号
    //double *p;
    //int i, m;
    //printf("please enter the number of student:");
    //scanf("%d",&m);//输入要查询的学生序号
    //printf("The sorces of No %d are : \n",m);
    //p = search(sorce, m);     //调用指针函数 返回一个地址
    //for ( i = 0; i < 4; i++)
    //{
    //    printf("%5.2f\t",*( p +  i ));
    //}
    //printf("\n\n\n");

    //char *a;
    //a = "abc";
    //char a[]={"abc"};
    //printf("%s",a);



    //char str[10];
    //scanf("%s",str);

    //char *a;   //没有赋初值会随机指向  （不行）
    //scanf("%s",a);
    #endif  //用指针函数输出学生的全部成绩

    #if( 0 )
    int a[3][4] = {{1,9,5,13},{23,8,49,2},{30,15,20,6}};
    int (*p)[4],max,i,j,k = 0,t = 0;
    p = a ;
    max = a[0][0];
    for ( i = 0; i < 3; i++)
    {
        for ( j = 0; j < 4; j++)
        {
            if(*(*(p+i)+j) > max)
                max = (*(*(p+i)+j))
                ,k = i, t = j;
                
        }
    }

    printf("max = %d , k = %d , t = %d",max,k,t);
    #endif    //利用行指针求二维数组中的最大值及其下标值

    #if( 0 )
    int i,a[10],*p,max ,min , k = 0, t = 0, temp = 0;
    p = a;
    for ( i = 0; i < 10; i++)
    {
        scanf_s("%d",p++);
    }
    p = a;
    max = min = a[0];
    for ( i = 0; i < 10; i++)
    {
        if(*(p+i)> max){
            max =  *(p+i), t = i ;

        }
    }
            temp = a[9];
            a[9] = max;
            a[t] = temp;


    for ( i = 0; i < 10; i++)
    {
        if(*(p+i) < min){
            min =  *(p+i), k = i ;
        }
    }
            temp = a[0];
            a[0] = min;
            a[k] = temp;
     for ( i = 0; i < 10; i++)
     {
         printf("%3d",*p++);
     }
    #endif    //输入10个数，将其中最小的数与第一个数对换，最大数与最后一个数对换
    
    #if( 0 )

     int a[3][4] = {{1,9,5,13},{23,8,49,2},{30,15,20,6}};
     int (*p)[4], i, j, min, k = 0 , t = 0;
     p = a;
     min = a[0][0];
     for ( i = 0; i < 3; i++)
     {
         for ( j = 0; j < 4; j++)
         {
             if ( min > *(*(p+i)+j))
                 min = *(*(p+i)+j), k = i, t = j;
                
         }
     }
     printf("min = %d, k = %d , t = %d",min , k , t);
                                                  
    #endif    //最小值及最小值下标

    #if( 0 )
     char *p = "hello";
     int i = 0;
     while (p[i] != '\0')
     {
         i++;
     }
     printf("%d\n",i);
    //char *p = "hello" ;
    //int i = 0;
    //while (*p != '\0')
    //{
    //    p++;
    //    i++;
    //}
    //printf("%d\n",i);
    #endif    //计算字符串长度（不调用strlen）

    #if( 0 )
     //char s[10], *p = "Chinese";
     //int i = 0;
     //while (p[i] != '\0')
     //{
        // s[i] = p[i];
        // i++;
     //}
     //s[i] = '\0';
     //printf("%s",s);
    #endif    //不调用strcpy 复制字符串

    #if( 0 )
     char *t[3] = {"google","baidu","yahoo"}, *s[3], *min;
     int i= 0;
     for ( i = 0; i < 3; i++)
     {
         s[i] =  t[i];
     }
     if (strcmp(s[0],s[1]) < 0  && strcmp(s[0],s[2]) < 0)
     {
        min = s[0];
     }
     if (strcmp(s[1],s[0]) < 0  && strcmp(s[1],s[2]) < 0)
     {
        min = s[1];
     }
     if (strcmp(s[2],s[0]) < 0  && strcmp(s[2],s[1]) < 0)
     {
        min = s[2];
     }
      printf("%s\n",min);

    #endif    //输出三个字符串中最小的字符串

    #if( 0 )
    int add(int x);
    int n, sum = 0;
    scanf("%d",&n);
    sum = add(n);
    printf("1 - %2d sum is %d",n,sum);
    #endif  //（递归）计算1+2+3+4 、、、 +n的值

    #if( 0 )

    void f(int *x,int *y);
    int a[8] = {1,2,3,4,5,6,7,8},i = 0, *p , *q;
    p = a; q = &a[7];
    while (*p!=*q && i<8)
    {
        f(p,q); p++; q--; i++; //p从首地址加到&a[7] q从&a[7]减到首地址 i=7时   i=8时 *p = *q = -858993460
    }
    for ( i = 0; i < 8; i++)
    {
        printf("%d",a[i]);
    }
    #endif  //指针练习题

    #if( 0 )
    int subString(char *a,char *b), num;
    char  *p = "deffafaddd", *q = "da";
    num  = subString(p,q);
    printf("%d",num);
    #endif  //查找一个子串在字符串中出现的个数

    #if( 0 )
    int  x = 0, i ,m = 0 , n = 0 ;
    for ( i = 1; i <=99 ; i++)
    {
        if( i < 10){
        x = pow((double)i,2);
        m = x % 10;
        n = x /10;
        if(i == m || i == n) printf("%d 和 %d 是同构数\n",i,x);
        }
        else
        {
            x = pow((double)i,2);
            //n = x /10 ;
            m = x%10+(x/10%10*10);
            if(i == m ) printf("%d 和 %d 是同构数\n",i,x);
        }
    }
        
    #endif    //同构数 

    #if( 1 )
    //int i, x = 0 , y;
    //for ( y = 0, x = 1;x > ++y; x = i++ )
    //{
    //    i = x;
    //}


    //int i , b ,k = 0;
    //for ( i = 1; i <=5 ; i++)
    //{
    //    b = i % 2;
    //    while (b-->=0) k++;
    //}
    //printf("%d %d",k,b);
    
    //int i = 32767;
    //do
    //{
    //    if(i<0) break; 
    //} while (++i);

    //int i = 1, j = 1;
    //do
    //{
    //    if(i % 3 == 2 && i % 5 == 3 && i % 7 ==2)
    //        printf("%4d",i);
    //    j = j +1;    
    //    if(j % 5 == 0) printf("\n");
    //            
    //        
    //    i = i +1;    
    //    
    //} while (i<1000);

//int i,j;
// for(i=0;i<=3;i++)
// {for(j=0;j<=5;j++)
// if(i==0||j==0||i==3||j==5) printf("*");
// else printf(" ");
// printf("\n");
// }

//char a[]="morning",t;
// int i,j=0;
// for(i=1;i<7;i++)
//if(a[j]<a[i]) 
//j=i;
//t=a[j];
//a[j]=a[7];
//a[7]=t;
//puts(a);



    #endif

    return 0;
}

    int power(int a, int b) //自定义pow函数
    {
        int i,c = 1;
            for (i = 0; i < b; i++)
            {
                c *= a;
            }
        return c;
    }
    int square(int x) //平方函数
    {    
        int z;
        z = x * x;
        return z;
    }
    int factorical(int y) //阶乘函数
    {
        int i,num=1;
        for ( i = 1; i <= y; i++)
        {
             num *= i;
        }
        return num;
    }
    int factorical2(int n) //递归 阶乘函数
    {
        int num=1;
        if(n < 0)
        {
        printf("Input error");
        }
        else if(n == 0 || n == 1 )
        {
            num = 1;
        }
        else
        {
            num = n * factorical2(n - 1); 
        }
        return num;
    }
    void hanoi(int n , char x , char y , char z ) //汉诺塔
    {
        if (n == 1)
        {
            printf("%c => %c\n",x,z);
        }
        else
        {
            hanoi(n-1 , x , z , y);
            printf("%c => %c\n",x,z);
            hanoi(n-1 , y , x , z);
        }
    }
    void average(int grade[]) //求平均成绩
    {
        int sum = 0 , i;
        for ( i = 0; i < 10; i++)
        {
            sum += grade[i];
        }
        printf("%g\n",sum / 10.0);
    }
    int fac(int a) //使用静态变量求阶乘
    {
        static int b = 1;
        b = b * a;
        return b;
    }
    extern void removestr(char str[],char char2)
    {
        int i,j;
        for ( i = j = 0; str[i] != '\0'; i++)
        {
            if(str[i] != char2)
            {
                str[j++] = str[i];
            }
        }
            str[j] = '\0';
            puts(str);
    } 
    void reverse(int x[],int n)
    {
        int m, j, i, temp;
        m = (n - 1) / 2;
        for ( i = 0; i < m; i++)
        {
            j = n - 1 - i;
            temp  = x[i];
            x[i] = x[j];
            x[j] = temp;

        }
    }
    void reverse1(int *x,int n)
    {
        int m, *j, *i, *p,temp;
        m = (n - 1) / 2;
        i = x;            // 数组元素第一个元素的地址 （i指向数组的第一个元素）
        j = x+n-1;        // 数组元素最后一个元素的地址
        p = x + m;        // 数组元素中间一个元素的地址
        for (; i <= p; i++, j--)
        {
            temp = *i;
            *i = *j;
            *j = temp;
        }
    }
    void sort(int a[], int n)
    {
       int  temp, i, j;
       bool flag = false;
       for ( j = 0; j < n-1; j++)
       {
           for ( i = 0; i < 9-j; i++)
           {
               if(a[i] < a[i+1])
               {
                    temp = a[i];
                    a[i] = a[i+1];
                    a[i+1] = temp;
                    flag = true;
               }
           }
           if(!flag)
           {
               break;
           }
       }
        //int i,j,k,t;
        //for ( i = 0; i < n-1; i++)
        //{
        //    k = i ;
        //    for ( j = i+1; j < n; j++)
        //    {
        //        if(a[j] > a[k])
        //        {
        //             t = a[j];
        //             a[j] = a[k];
        //             a[k] = t;    
        //        }
        //    }
        //}

      
    }
    void sort1(int *a, int n)
    {
        //int i,j,k,t;
        //for ( i = 0; i < n-1; i++)
        //{
        //    k = i ;
        //    for ( j = i+1; j < n; j++)
        //    {
        //        if(a[j] > a[k])
        //        {
        //             t = a[j];
        //             a[j] = a[k];
        //             a[k] = t;    
        //        }
        //    }
        //}

        int *i, *j, *k ,t;
        for ( i = a; i < a+n-1; i++)
        {
            k = i;
            for ( j = i + 1; j < a + n; j++)
            {
                if(a[*j] > a[*k])
                {
                    t = a[*j];
                    a[*j] = a[*k];
                    a[*k] = t;
                }
            }
        }
    }
    void copy(char a[],char b[])
    {
        int i = 0;
        for (;  b[i] != '\0'; i++)
        {
              b[i] = a[i] ;
        }
            b[i] = '\0';

    }
    void copy1(char *a,char *b)
    {
        for (;  *b != '\0'; a++,b++ )
        {
             *b = *a;
        }
            *b = '\0';
    }
    /*
    int max (int x, int y)
    {
     if(x>y)
         return x;
     else
         return y;
    }
    int min (int x, int y)
    {
        if(x > y)
        return y;
        else
        return x; 
    }
    int add (int x, int y)
    {
        int z;
        z = x + y;
        return z;
    }*/
    void process(int x,int y,int (*fun)(int,int) )
    {
        printf("%d",(*fun)(x,y));
    }
    double *search(double (*pointer)[4], int n)
    {
        double *pt;
        pt = *(pointer + n);
        return pt;
    }
    /*triangle
    double area (double x1, double y1)
    {
        return  x1 * y1 * 0.5;
    }
    double length (double x2, double y2)
    {
        return sqrt(x2 * x2 + y2 * y2);
    }
    double cal(double x3, double y3, double (*p)(double x4, double y4))
    {
        return (*p)(x3,y3);
    }
    */ 
    int add(int x)
    {
        int sum = 0;
        if(x == 1)
        {
            x = 1;
        }
        else
        {
            sum += 1 + x + add(x-1);
        }
        return sum;
    }
    void f(int *x,int *y)
    {
        int t;
        t = *x; *x = *y; *y = t;
    }
    int subString(char *a,char *b)
    {
        int i , j, n = 0;
        for ( i = 0; i < 10; i++)
        {
            for ( j = 0; j < 10; j++)
            {
                if(a[i] != '\0' && b[i] != '\0' )
                if(a[i] == b[j])
                {
                    n++;
                }
            }
        }
        return n;
    }