自己写一个swap函数交换任意两个相同类型元素的值 对空指针的使用 字节大小的判断（一）

#include <stdio.h>
struct Point{
    int x;
    double y;
    Point(int x = 0, double y = 0):x(x), y(y){}
    void print(){
        printf("(%d, %lf)", x, y);
    }
};
void swap (char *a, char *b, size_t width){
    char tmp;
    while(width--){
        tmp = *a;
        *a++ = *b;
        *b++ = tmp;
    }
}
//width是交换两个元素的字节大小，用sizeof 求出
void myswap(void *x, void *y, size_t width){
    swap((char *)x, (char *)y, width);
}
int main(){
    int inta = 1, intb = 2;
    printf("before exchange: inta=%d\tintb=%d\n", inta, intb);
    //交换整形inta和intb的值
    myswap(&inta, &intb, sizeof(int));
    printf("after  exchagge: inta=%d\tintb=%d\n", inta, intb);

    char chara = 'a', charb = 'A';
    printf("before exchange: chara=%c\tcharb=%c\n", chara, charb);
    //交换字符chara和字符charb的值
    myswap(&chara, &charb, sizeof(char));
    printf("after  exchagge: chara=%c\tcharb=%c\n", chara, charb);

    Point pointa(1, 1.1), pointb(3, 3.3);
    printf("before exchange: pointa="); pointa.print(); 
    printf("\tpointb="); pointb.print(); printf("\n");
    //交换结构体pointa和pointb的值
    myswap(&pointa, &pointb, sizeof(Point));
    printf("before exchange: pointa="); pointa.print(); 
    printf("\tpointb="); pointb.print(); printf("\n");
    return 0;
}

程序运行结果