C语言学习第18篇---值和引用函数的区别

值调用;

#include <stdio.h>

void change(int num) {

printf("Before adding value inside function num=%d \n", num);

num = num + 10;

printf("After adding value inside function num=%d \n", num);}

int main() {

int x = 10;

// 更新之前参数x的值

printf("Before function call x=%d \n", x);

change(x); // passing value in function

// 更新之后参数x的值

printf("After function call x=%d \n", x);

return 0;}

输出：

Before function call x=10

Before adding value inside function num=10

After adding value inside function num=20

After function call x=10 //原始值是没有改变的

引用调用：

#include <stdio.h>

// 定义函数，注意这里的参数名称前加了一个星号(*)void change2(int *num) {

printf("Before adding value inside function num=%d \n", *num);

(*num) += 100;

printf("After adding value inside function num=%d \n", *num);}

int main() {

int x = 200;

printf("Before function call x=%d \n", x);

// 注意，下面传递的参数名称前加了一个符号(&)

change2(&x);// passing reference in function

printf("After function call x=%d \n", x);

return 0;}

输出：

Before function call x=200

Before adding value inside function num=200

After adding value inside function num=300

After function call x=300 //被改变了