getline 函数与头文件的关系

请教各位!

1:在那些头文件下
使用那些getline函数(比如cin.getline,file.getline,getline....等)?
2:极其cin.getline,file.getline,getline的用法异同?

[此贴子已经被作者于2006-11-14 17:36:14编辑过]

说错了

[此贴子已经被作者于2006-11-14 18:36:36编辑过]

那怎样读入部分数据，比如只读二到三行

istream::getline
istream& getline( char* pch, int nCount, char delim = '\n' );

istream& getline( unsigned char* puch, int nCount, char delim = '\n' );

istream& getline( signed char* psch, int nCount, char delim = '\n' );

Parameters

pch, puch, psch

A pointer to a character array.

nCount

The maximum number of characters to store, including the terminating NULL.

delim

The delimiter character (defaults to newline).

举个例子吧：

ifstream &is;
string textline;
getline(is,textline);

用国语解释哈