面试题5：替换空格

class Solution {
public:
    //length为字符数组的总容量
    void replaceSpace(char *str,int length) {
        if(str == nullptr || length <= 0)
            return;
        int originalLen = 0;
        int blankLen = 0;
        int i = 0;
        while(str[i] != ‘\0‘)
        {
            ++originalLen;
            if(str[i] == ‘ ‘)
                ++blankLen;
            ++i;
        }
        int newLen = originalLen + blankLen * 2;
        if(newLen > length)
            return;
        while(originalLen >= 0 && newLen > originalLen)
        {
            if(str[originalLen] == ‘ ‘)
            {
                str[newLen--] = ‘0‘;
                str[newLen--] = ‘2‘;
                str[newLen--] = ‘%‘;
            }
            else
            {
                str[newLen--] = str[originalLen];
            }
            --originalLen;
        }
    }
};