//字符串替换空格:实现一个函数，把字符串里的空格替换成“%20”#include 
     
      #include 
      
       void replace(char *src){	assert(src);	int OldLen = 0;                  //原字符串长度	int NewLen = 0;                  //新字符串长度	int BlackNum = 0;                //空格数量	int NewBack = 0;                 //新字符串尾部	int OldBack = 0;                 //原字符串尾部	while (src[OldLen] != '\0')	{		if (src[OldLen] == ' ')		{			BlackNum++;		}		OldLen++;	}	NewLen = OldLen + BlackNum * 2;	OldBack = OldLen-1;	NewBack = NewLen - 1;	while (OldBack!=0)	{		if (src[OldBack] == ' ')		{			src[NewBack--] = '0';			src[NewBack--] = '2';			src[NewBack] = '%';		}		else		{			src[NewBack] = src[OldBack];		}		OldBack--;		NewBack--;	}}int main(){	char p[20] = "hello world !";	replace(p);	printf("%s\n", p);	return 0;	return 0;}