《剑指offer》面试题4 替换空格为%20

#include<stdio.h>#include<stdlib.h>#include<string.h>void change_space(char *str){  int i = 0;  int n = 0;  int len = strlen(str);// strlen 字符串操作函数，求取字符串长度  int nlength = 0; while(len) {   if(*str == ' ')   {     n++;   }   len--;   str++; }   nlength = len + n*2;  while(len!=nlength)  {   if(str[len] == ' ')  {        str[nlength--] = '0';str[nlength--] = '2';str[nlength--] = '%';len--;  }  else  {  str[nlength--] = str[len--];  }  }}  int main()  {char p[50]="i am a student";change_space(p);printf("%s",p);system("pause");    return 0;  }