OC手写的字符串的拼接

调用代码

NSString *a = @"abc";
    NSString *b = @"def";
    //手写的字符串的拼接
    char *c = str_cat([a UTF8String], [b UTF8String]);

实现代码

char *str_cat(const char *str1, const char *str2){
    int len1 = 0;
    int len2 = 0;
    for (len1 = 0; *(str1+len1) != '\0'; len1++){} //获取str1长度
    for (len2 = 0; *(str2+len2) != '\0'; len2++){} //获取str2长度
    char *ret = (char *)malloc(sizeof(char)*(len1+len2+1)); //申请动态空间
    /*内存赋值*/
    int i;
    for (i=0; i<len1; i++){
        *(ret+i) = *(str1+i);
    }
    for (i=0; i<len2; i++){
        *(ret+len1+i) = *(str2+i);
    }
    *(ret+len1+len2) = '\0';
    
    return ret;
}