c语言中函数的定义和调用（值传递，计算x的n次幂）

1、值传递，计算x的n次幂

#include <stdio.h>

double power(double x, int n)
{
    int i;
    double tmp = 1.0;
    
    for (i = 1; i <= n; i++)
    {
        tmp *= x;
    }
    return tmp;
}

int main(void)
{
    double a;
    int b;
    puts("please input the value of a and b.");
    printf("a = "); scanf("%lf", &a);
    printf("b = "); scanf("%d", &b);
    
    printf("result = %.3f\n", power(a, b));
    return 0;
}

↓

#include <stdio.h>

double power(double x, int n)
{
    double tmp = 1.0;
    
    while (n-- > 0)
    {
        tmp *= x;
    }
    return tmp;
}

int main(void)
{
    double a;
    int b;
    puts("please input the value of a and b.");
    printf("a = "); scanf("%lf", &a);
    printf("b = "); scanf("%d", &b);
    
    printf("result = %.4f", power(a, b));
    return 0;
}

 ↓

#include <stdio.h>

double power(double x, int n)
{
    double tmp = 1.0;
    
    for (n; n > 0; n--)
    {
        tmp *= x;
    }
    return tmp;
}

int main(void)
{
    double a;
    int b;
    puts("please input the value of a and b.");
    printf("a = "); scanf("%lf", &a);
    printf("b = "); scanf("%d", &b);
    
    printf("result = %.3f", power(a, b));
    return 0;
}