算法实现c语言--03

1. 实现  mystrcpy(), mystrcmp(), mystrcat(), mystrlen() ;

   #include<stdio.h>
   #include<stdlib.h>
   
   int mystrlen(char *c)
   {
       int i=0;
       while (c[i]!='\0')i++;
       return i;
   }
   int mystrcmp(char *c1,char *c2)
   {
       int i = 0, j = 0;
       for (; c1[i] != '\0'&&c2[i] != '\0'; i++)
       {
           if (c1[i] < c2[i])return -1;
           else if (c1[i] == c2[i])continue;
           else return 1;
       }
       return 0;
   }
   char* mystrcopy(char *c1, char *c2)
   {
       int i = 0, j = 0;
   
       while (c2[j] != '\0')c1[i++] = c2[j++];
   
       c1[i] = '\0';
       return c1;
   }
   char* mystrcat(char *c1, char *c2)
   {
   
       int i = 0, j = 0;
       while (c1[i] != '\0')i++;
   
       while(c2[j] != '\0')c1[i++] = c2[j++];
   
       c1[i] = '\0';
       return c1;
   }
   int main()
   {
       char c1[100] = "hello ", c2[100] = "woel";
       printf("%d\n",mystrlen(c1));
       printf("%d\n", mystrcmp(c1, c2));
       mystrcat(c1, c2);
       printf("%s\n", c1);
       mystrcopy(c1, c2);
       printf("%s\n", c1);
   
       system("pause");
       return 0;
   }

   2.输入一行字符串（单词和若干空格）， 输出该行单词个数。

   Input：____hello_________world_ how___are___you___\n

   　　Output:   5

#include<stdio.h>
#include<stdlib.h>

int fun(char *c) 
{
    int i = 0,cnt=0;
    while (c[i] != '\0')
    {
        if (c[i] == ' ')
        {
            i++;
            if (c[i] != ' ')cnt++;
        }
        else i++;
        
    }
    return cnt;
}

int main()
{
    char c1[100] = "hello world how are you ";
    puts(c1);
    printf("%d",fun(c1));


    system("pause");
    return 0;
}

3.输入一行字符串（单词和若干空格），输出该行单词（每个单词一行）

Input：____hello_________world_ how___are___you___\n

Output:   hello

                world

                how

                are

                       You

#include<stdio.h>
#include<stdlib.h>

void fun(char *c) 
{
    int i = 0,cnt=0;
    while (c[i] != '\0')
    {
        if (c[i] == ' ')
        {
            i++;
            continue;
        }
        if (c[i] != ' ')
        {
            printf("%c", c[i]);
            i++;
            if (c[i] == ' ')printf("\n");
        }
        
    }
}

int main()
{
    char c1[100] = "hello world how are you ";
    puts(c1);
    fun(c1);


    system("pause");
    return 0;
}

4.输入一行字符串，把字符串翻转 。

Input: I____am__a__student

Output: student__a__am____I

 

1、直接翻转一下

2、把每个单词找出来，原地自身翻转

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

void fun1(char *c)
{
int i = strlen(c) - 1;

while (i >= 0)
{
printf("%c", c[i]);
i--;
}
//printf("\n");
}
void strcut(char *s, char *sub) //用参数sub来保存结果，所以函数不用返回值了
{
int i=0, j = 0, k = 0;
for (i = strlen(s)-1; i >=0 ; i--)
{
//printf("%c", s[i]);
if (s[i] != ' ')
{
sub[j++] = s[i];
if (s[i-1] == ' '||i==0)
{
sub[j] = '\0';
fun1(sub); printf(" ");
j = 0;
}

}

}
}

int main()
{
char c1[] = "hello world how are you ";
puts(c1);
fun1(c1);
printf("\n");
char ps[100]; //用来保存截取子串的必须是数组，不能是指针
static char s[] = "hello world how are you ";
strcut(s, ps);
//printf("%s\n", ps);
system("pause");
return 0;
}