剑指offer面试题5：替换空格

#include <iostream>
using namespace std;
void ReplaceBlank(char string[],int length)
{
    if(string==nullptr || length<0)
        return;
    
    int originalLength=0;
    int numberOfBlank=0;
    int i=0;
    while(string[i]!='\0')
    {
        ++originalLength;
        if(string[i]==' ')
            ++numberOfBlank;
        ++i;
    }
    
    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--;
    }
}
int main()
{
    char string[20]="we are happy";
    ReplaceBlank(string, 20);
    cout<<string<<endl;
}