每日一題--空格替換

//1.題目把字符串中空格替換成 %20
//分析：
//循環遍歷字符串，統計字符串個數
//根據空格個數延長字符串
//遍歷字符串，替換空格符
void* repalceSpace(char *str ,int len)
{
    int count = 0;
    char* tmp = str;
    while (*tmp!='\0')
    {
        if (*tmp == ' ')
            count++;
        tmp++;
    }
    int newsize = len + 2 * count;
    str[newsize] = '\0';

    char*end = str + len - 1;
    char*new_end = str + newsize - 1;
    while (end != new_end)
    {
        if (*end != ' ')
            *new_end-- = *end;
        else
        {
            *new_end-- = '0';
            *new_end-- = '2';
            *new_end-- = '%';
            end--;
        }
    }
    return str;
}