字符串复制和比较函数的实现

#include<stdio.h>#include<string.h>#define N 50//字符串复制函数1，数组法（用虚数组做形参，以下标法访问元素）void strcpy1(char s1[], char s2[]){int i = 0;while(s1[i] = s2[i])i++;}//字符串复制函数2，指针法（用字符指针做形参，以指针法访问元素）void strcpy2(char *s1, char *s2){while(*s1++ = *s2++);}//字符串比较函数，数组法int strcmp1(char s1[], char s2[]){int i= 0;while(s1[i] == s2[i]){if(s1[i] == 0)return 0;i++;}return (s1[i] - s2[i]);}//字符串比较函数，指针法int strcmp2(char *s1, char *s2){while(*s1 == *s2){if(*s1 == 0)return 0;s1++;s2++;}return (*s1 - *s2);}int main(void){char str1[] = "welcome to Hello World!", str2[N], str3[N];char st1[] = "welcome to China!", st2[] = "welcome to hello world!";strcpy1(str2, str1);puts(str2);printf("************************\n");strcpy2(str3, str1);puts(str3);printf("************************\n");strcpy1(str2 + 11, "Beijing");puts(str2);printf("************************\n");printf("str1: ");puts(str1);printf("st1: ");puts(st1);printf("st2:");puts(st2);printf("\nstr1与st1的比较结果：%d\n",strcmp1(str1, st1));printf("\nstr1与st2的比较结果：%d\n",strcmp2(str1, st2));printf("\nstr1与str2的比较结果：%d\n",strcmp2(str1, str2));}