strcpy; strcmp; strlen; strcat 函数实现

来源：互联网发布：极光卡五星源码出售编辑：程序博客网时间：2024/05/22 04:48

#include<stdio.h>#include<assert.h>/*strcpy函数的实现*/char *strcpy(char *strDest, const char *strSrc){assert((strDest != NULL) && (strSrc != NULL));char *cp = strDest;while(*strSrc){*strDest++ = *strSrc++;}*strDest = '\0';return cp;}/*strncpy函数的实现*/char *strncpy(char *strDest, const char *strSrc, int count){assert((strDest != NULL) && (strSrc != NULL));char *cp = strDest;int i = 0;while(*strSrc && i < count){*strDest++ = *strSrc++;i++;}*strDest = '\0';return cp;}/*strcmp函数的实现*/int strcmp(const char *str1,const char *str2){assert((str1 != NULL) && (str2 != NULL));while(*str1 && *str2 && (*str1 == *str2)){str1++;str2++;}return *str1 - *str2;}/*strlen函数的实现*/int strlen(const char *str){int len = 0;assert(str != NULL);while(*str++){len++;}return len;}/*strcat函数的实现*/char *strcat(char *strDesc, const char *strSrc){char *cp = strDesc;while(*cp){cp++;}while(*strSrc){*cp++ = *strSrc++;}*cp = '\0';return strDesc;}