剑指offer<二>替换空格

剑指offer<二>替换空格

题目描述

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。

先统计出远来得字符串长度，再计算出现在的字符串长度；然后从后往前，一次赋值，遇到空格，用%20填充

class Solution {

public:

void replaceSpace(char *str,int length) {

int cout = 0;

        int i =0,oldnumber = 0;

        if(str == NULL || length < 0)

            return ;

        while(str[i]!='\0')

        {

            oldnumber ++;

           if(str[i] == ' ')

              cout++;

            i++;

        }

        int newnumber = oldnumber+cout*2;

        if(newnumber < oldnumber)

            return ;

        int newindex = newnumber;

        int oldindex = oldnumber;

        while(newindex>=0 && newindex > oldindex)

            {

             if(str[oldindex] == ' ')

                    {

                     str[newindex--] = '0';

                    str[newindex--] = '2';

                    str[newindex--] = '%';

                    

                }

            else

            {

                

                str[newindex--] = str[oldindex];

            }

            --oldindex;

             

        }

        

}

};