[LeetCode]-344. Reverse String(Easy)(C)

344. Reverse String

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Total Accepted: 11974  Total Submissions: 20496  Difficulty: Easy

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "hello", return "olleh".

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题目的意思很简单，给你一个字符串，让你把这个字符串的逆序输出来，是一道很初学者经常会见到的题目，我这里选择C语言来写.

代码如下：

char *reverseString(char *s){
    int i = strlen(s)-1;                                //创建变量i，记录字符串的长度再减去1，作为此时字符数组的下标
    if(i>=0){                                           //如果字符串的长度大于等于0
        char *str =(char*)malloc(strlen(s)+1);          //给字符指针str分配内存,为字符串的长度+1，其中多的1位是为了'\0'分配的
        do{
            *str = s[i];                                //逆序拷贝
            str++;                                      //str下标++
        }while(i--);                                    //s下标--
        *str = '\0';                                    //此时str = 0,将其赋值为'\0'
        str = str-strlen(s);                            //此时str指针指向最后一位'\0',指针向前移动字符串的长度，归位
        s = str;                                        //将str指针赋值给s，拷贝str的首地址
    }
    return s;                                           //返回s的首地址
}