字符串替换

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


  void replaceSpace( char *str, int length) {

          if (str==NULL)

              return ;

          int CountOfBlanks=0;

          int Originallength=0;

          for ( int i=0;str[i]!= '\0' ;i++)

              {

              Originallength++;

              if (str[i]== ' ' )

                  ++CountOfBlanks;

          }

          int len =Originallength+2*CountOfBlanks;

          if (len+1>length)

              return ;

          

          char *pStr1=str+Originallength; //复制结束符‘\0’

          char *pStr2=str+len;

         while (pStr1<pStr2)

             {

             if (*pStr1== ' ' )

                 {

                 *pStr2--= '0' ;

                 *pStr2--= '2' ;

                 *pStr2--= '%' ;    

             }

             else

              {

                  *pStr2--=*pStr1;

             }

             --pStr1;

         }

     }