剑指offer-002

请实现一个函数，将一个字符串中的空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy.

class Solution {
public:
void replaceSpace(char string[] ,int length) {
if(string == NULL || length <= 0)
return ;

    int originalLength = 0;
    int numberBlank = 0;
    int i =0;
    while(string[i] != '\0')
        {
        ++originalLength;
        if(string[i] == ' ')
            ++numberBlank;
            ++i;
    }
    int newLength = originalLength + numberBlank * 2;
    if(newLength > length)
        return ;
    int indexOriginal = originalLength;
    int indexNew = newLength;
    while(indexOriginal >= 0 && indexNew > indexOriginal)
        {
        if(string[indexOriginal] == ' ')
            {
            string[indexNew --] = '0';
            string[indexNew --] = '2';
            string[indexNew --] = '%';
         }
        else{
            string[indexNew --] = string[indexOriginal];
        }
        --indexOriginal;
    }
}

};