当然用Java或C#，C++中自带的库函数很轻松就可以实现，这里用C语言，没用库函数的实现
/*
把一个字符串的空格替换成20%
*/
#include <stdio.h>
#define maxLength 100
int main()
{
char str[maxLength];
int i,countSpace=0,strLength,newLength,temp;
gets(str);
strLength = strlen(str);
for(i=0;i<strLength;i++)
{
if(str[i]==' ')
{
countSpace++;
}
}
newLength = strLength + countSpace*2;
temp = newLength;
for(i=strLength-1;i>=0;i--)
{
if(str[i]==' ')
{
str[newLength-1] = '%';
str[newLength-2] = '0';
str[newLength-3] = '2';
newLength -=3;
}else
{
str[newLength-1] = str[i];
newLength--;
}
}
for(i=0;i<temp;i++)
{
printf("%c",str[i]);
}
printf("\n");
return 0;
}