C 字符串相加

#include <stdio.h>#include <string.h>#include <stdlib.h>char * join1(char *str1, char *str2);char * join2(char *str1, char *str2);int main(){char *str1 ="abc";char *str2 = "def";char *result = join2(str1, str2);if(result == NULL){printf("error\n");return 0;}printf("%s\n", result);free(result);result = NULL; return 0;}char * join1(char *str1, char * str2){char *result = (char *)malloc(strlen(str1) + strlen(str2) + 1);char *c = result;if(result == NULL)return NULL;while(*str1 != '\0'){*result++ = *str1++;}while(*str2 != '\0'){*result++ = *str2++;}return c;}/*调用库函数*/char *join2(char *str1, char *str2){char *result = (char *)malloc(strlen(str1) + strlen(str2) + 1);if(result == NULL)return NULL;strcpy(result, str1);printf("%s\n", result);strcat(result, str2);return result;}