实验3

任务1.1

#include<stdio.h>
long long fac(int n);
int main()
{
    int i, n;
    printf("Enter n:");
    scanf("%d", &n);
    for (i = 1; i <= n; ++i)
    {
        printf("%d!=%lld\n", i, fac(i));
    }
        return 0;
}
long long fac(int n) 
{
    static long long p = 1;
    p = p * n;
    return p;
}

 任务1.2

#include<stdio.h>
int func(int, int);
int main()
{
    int k = 4, m = 1, p1, p2;
    p1 = func(k, m);
    p2 = func(k, m);
    printf("%d,%d\n", p1, p2);
    return 0;
}

int func(int a, int b)
{
    static int m = 0, i = 2;
    i += m + 1;
    m = i + a + b;
    return (m);
}

局部static变量：静态变量，在函数调用结束后变量的值不会变为初始值。 

任务2.1

 

#include<stdio.h>
void printSymbol(int n, char symbol);
int main()
{
    int n;
    char symbol;
    while (scanf("%d %c", &n, &symbol) != EOF)
    {
        printSymbol(n, symbol);
        printf("\n");
    }
    return 0;
}
 void printSymbol(int n,char symbol)
{
     if (n == 1)
     {
         printf("%c", symbol);
     }
    if (n >= 2)
    {
        printf("%c", symbol);
        return printSymbol(n - 1, symbol);
    }
}

 任务2.2

#include<stdio.h>
void printSymbol(int n, char symbol);
int main()
{
    int n;
    char symbol;
    while (scanf("%d %c", &n, &symbol) != EOF)
    {
        printSymbol(n, symbol);
        printf("\n");
    }
    return 0;
}
void printSymbol(int a, char b)
{
    int i = 1;
    for (i = 1; i <= a; i++)
    {
        printf("%c", b);
    }
}

 任务3

#include<stdio.h>
long long fun(int n);
int main()
{
    int n;
    long long f;
    while (scanf("%d", &n) != EOF)
    {
        f = fun(n);
        printf("n=%d,f=%lld\n", n, f);
    }
    return 0;
}
long long fun(int a)
{
    if (a == 1)
        return 1;
    if (a >= 2)
        return 2*fun(a - 1)+1;
}

 任务4

#include<stdio.h>
#include<math.h>
int isprime(int n);
int main()
{   
    int i=101,m=0;
    for (i = 101; i <= 200; i++)
    {
        if (!isprime(i))
        {
            m += 1;
            printf("%5d", i);
            if (m % 10 == 0)
                printf("\n");
        }
    }
    printf("\n101~200之间一共有%d个非素数", m);
    return 0;
}
int isprime(int a)
{
    int b = 2;
    for (b = 2; b <= sqrt(a); b++)
        if (a % b == 0)
            return 0;
    return 1;
}

任务5

 

#include<stdio.h>
#include<math.h>
long fun(long s);
int main()
{
    long s, t;
    printf("Enter a number:");
    while (scanf("%ld", &s) != EOF)
    {
        t = fun(s);
        printf("new number is:%ld\n\n", t);
        printf("Enter a number: ");
    }
    return 0;
}
long fun(long a)
{
    long long s=0;
    int b[100] = { 0 };
    int i = 0,c=0,n=0;
    while (a != 0)
    {
        b[i] = a % 10;
        a /= 10;
        i++;
        n++;
    }
    for (i=0;i<=n-1;i++)
    {
        if (b[i] % 2 != 0)
        {
            s += b[i] * pow(10, c);
            c++;
        }
    }
    return s;
}

任务6

#include<stdio.h>
double fun(int n);
int main()
{
    int n;
    double s;
    printf("Enter n(1~10):");
    while (scanf("%d", &n) != EOF)
    {
        s = fun(n);
        printf("n=%d,s=%f\n\n", n, s);
        printf("Enter n(1~10):");
    }
    return 0;
}
double fun(int n)
{
    int i = 1,b=1,c=1,d=1;
    double a=0.0;
    int k = 1;
    for (i = 1; i <= n; i++)
    {
        for (k = 1; k <= b; k++)
        {
            c =c*k;
        }
        a += 1.0 /c*d;
        d = -d;
        b++;
        c = 1;
    }
    return a;
}