大虾们,请问怎样循环接受一不确定数量的字符串啊???

[guoxt]

接受一字符串,并把他保存.但字符串的长度未知.知道最后打了回车后才退出.

用什么循环啊?循环条件怎么设置啊?
谢谢各位大虾了.

[improgrammer]

int main()
{
int N = 100;
int ch;
char *buf = new char[N];
for (int i=0; (ch = getchar()) != '\n'; ++i)
{
if (i >= N)
{
N += 100;
char *b = new char[N];
strcpy(b, buf);
delete[]buf;
buf = b;
}
buf[i] = ch;
}
printf("%s\n", buf);
delete[]buf;
return 0;
}