字符串拷贝函数的七种写法

#include<stdio.h>
#include<stdlib.h>

void copy_str(char* from, char* to){

    for (; *from != '\0'; from++,to++){
        *to = *from;
    }
    *to = '\0';//注意最后要记得拷贝'\0'
    return;
}

// ++ 优先级高  先执行*to = * from 然后加进行自加
void copy_str2(char* from, char* to){

    for (; *from != '\0';){
        *to++ = *from++;
    }
    *to = '\0';//注意最后要记得拷贝'\0'
    return;
}


void copy_str3(char* from, char* to){

    while ((*to = *from) != '\0'){
        from++;
        to++;
    }
}


void copy_str4(char* from, char* to){

    while ((*to++ = *from++) != '\0'){
        ;
    }
}

void copy_str5(char* from, char* to){

    while (*to++ = *from++){
        ;
    }
}

void copy_str6(char* from, char* to){
    if (from == NULL || to == NULL){
        return;
    }
    while (*to++ = *from++){
        ;
    }
}

//不要轻易改变形参的值，要引入一个辅助的指针变量，把形参接过来
void copy_str7(char* from, char* to){
    char *tmpfrom = from;//定义临时变量，防止错误操作对形参的修改
    char *tmptpo = to;
    if (tmpfrom == NULL || tmptpo == NULL){
        return;
    }
    while (*tmptpo++ = *tmpfrom++){
        ;
    }
    printf("%s", from);
}

void main(){
    char * from = "abcdfg";
    char buf2[100];

    copy_str5(from, buf2);
    printf("%s\n", buf2);

    system("pause");
}