剑指offer：替换空格

/*length 为字符数组string的总容量*/
void ReplaceBlank(char string[], int length)
{
    if(string == NULL && length <= 0)
        return;
    /*originalLength 为字符串string的实际长度*/
    int originalLength = 0;
    int numberOfBlank = 0;
    int i = 0;
    while(string[i] != ‘\0‘)
    {
        ++ originalLength;
        if(string[i] == ‘ ‘)
            ++ numberOfBlank;
        ++ i;
    }
    /*newLength 为把空格替换成‘%20‘之后的长度*/
    int newLength = originalLength + numberOfBlank * 2;
    if(newLength > length)
        return;
    int indexOfOriginal = originalLength;
    int indexOfNew = newLength;
    while(indexOfOriginal >= 0 && indexOfNew > indexOfOriginal)
    {
        if(string[indexOfOriginal] == ‘ ‘)
        {
            string[indexOfNew --] = ‘0‘;
            string[indexOfNew --] = ‘2‘;
            string[indexOfNew --] = ‘%‘;
        }
        else
        {
            string[indexOfNew --] = string[indexOfOriginal];
        }
        -- indexOfOriginal;
    }
}