以下程序（是变长输入的字符串）运行正常（在Vsiual Stdio 2005 中编译运行，操作系统是：windows2000)：而将有注释的一句移到while大括号外运行时出错。（本意是修改重复的赋值）。请高手指点这是为什么？
#include <iostream>
#include <cstring>
const int N=5;
int main()
{
char *s=new char[N];
char ch;
int n=0,j=1;
while(std::cin.get(ch)&&ch!='\n')
{
if(n==j*N-1)
{
char *temp=new char[n+1+N];
strcpy(temp,s);
delete []s;
s=temp;
j++;
}
s[n++]=ch;
s[n]='\0'; //移到下面的大括号外
}
std::cout<<s<<"\n";
delete []s;
return 0;
}
改动后的程序如下：
#include <iostream>
#include <cstring>
const int N=5;
int main()
{
char *s=new char[N];
char ch;
int n=0,j=1;
while(std::cin.get(ch)&&ch!='\n')
{
if(n==j*N-1)
{
char *temp=new char[n+1+N];
strcpy(temp,s);
delete []s;
s=temp;
j++;
}
s[n++]=ch;
}
s[n]='\0'; //移动的语句
std::cout<<s<<"\n";
delete []s;
return 0;
}
