按值传递 和 按地址传递的例子

#include <stdio.h>

void myswap(int, int);
void ptr_myswap(int*, int*);

int main(){
    int a, b;
    a = 3;
    b = 5;
    printf("in main, before call fun myswap(), a=%d; b=%d\n", a, b);
    myswap(a, b);
    printf("in main, after call fun myswap(), a=%d; b=%d\n\n", a, b);
    ptr_myswap(&a, &b);
    printf("in main, after call fun ptr_myswap(), a=%d; b=%d\n", a, b);

    return 0;
}

void myswap(int x, int y){
    int z;
    printf("in fun myswap(), before swap x=%d; y=%d\n", x, y);
    z = x;
    x = y;
    y = z;
    printf("in fun myswap(), after swap x=%d; y=%d\n", x, y);
}

void ptr_myswap(int* xPtr, int *yPtr) {
    int z;
    printf("in fun ptr_myswap(), before swap x=%d; y=%d\n", *xPtr, *yPtr);
    z = *xPtr;
    *xPtr = *yPtr;
    *yPtr = z;
    printf("in fun ptr_myswap(),after swap x=%d; y=%d\n", *xPtr, *yPtr);
}