使用ifstream和getline读取文件内容[c++]

假设有一个叫 data.txt 的文件, 它包含以下内容:

Fry: One Jillion dollars.
[Everyone gasps.]
Auctioneer: Sir, that's not a number.
数据读取, 测试 。


以下就是基于 data.txt 的数据读取操作:

#include <iostream>
#include 
<fstream>
#include 
<string>

using namespace std;

//输出空行
void OutPutAnEmptyLine()
{
    cout
<<"\n";
}


//读取方式: 逐词读取, 词之间用空格区分
//read data from the file, Word BWord
//when used in this manner, we'll get space-delimited bits of text from the file
//but all of the whitespace that separated words (including newlines) was lost. 
void ReadDataFromFileWBW()
{
    ifstream fin(
"data.txt");  
    
string s;  
    
while( fin >> s ) 
    
{    
        cout 
<< "Read from file: " << s << endl;  
    }

}


//读取方式: 逐行读取, 将行读入字符数组, 行之间用回车换行区分
//If we were interested in preserving whitespace, 
//we could read the file in Line-By-Line using the I/O getline() function.
void ReadDataFromFileLBLIntoCharArray()
{
    ifstream fin(
"data.txt"); 
    
const int LINE_LENGTH = 100
    
char str[LINE_LENGTH];  
    
while( fin.getline(str,LINE_LENGTH) )
    
{    
        cout 
<< "Read from file: " << str << endl;
    }

}


//读取方式: 逐行读取, 将行读入字符串, 行之间用回车换行区分
//If you want to avoid reading into character arrays, 
//you can use the C++ string getline() function to read lines into strings
void ReadDataFromFileLBLIntoString()
{
    ifstream fin(
"data.txt");  
    
string s;  
    
while( getline(fin,s) )
    
{    
        cout 
<< "Read from file: " << s << endl; 
    }

}


//带错误检测的读取方式
//Simply evaluating an I/O object in a boolean context will return false 
//if any errors have occurred
void ReadDataWithErrChecking()
{
    
string filename = "dataFUNNY.txt";  
    ifstream fin( filename.c_str());  
    
if!fin ) 
    
{   
        cout 
<< "Error opening " << filename << " for input" << endl;   
        exit(
-1);  
    }

}


int main()
{
    ReadDataFromFileWBW(); 
//逐词读入字符串 
    OutPutAnEmptyLine(); //输出空行

    ReadDataFromFileLBLIntoCharArray(); 
//逐词读入字符数组
    OutPutAnEmptyLine(); //输出空行

    ReadDataFromFileLBLIntoString(); 
//逐词读入字符串
    OutPutAnEmptyLine(); //输出空行

    ReadDataWithErrChecking(); 
//带检测的读取
    return 0;
}


输出结果为:
Read from file: Fry:
Read from file: One
Read from file: Jillion
Read from file: dollars.
Read from file: [Everyone
Read from file: gasps.]
Read from file: Auctioneer:
Read from file: Sir,
Read from file: that's
Read from file: not
Read from file: a
Read from file: number.
Read from file: 数据读取,
Read from file: 测试
Read from file: 。


Read from file: Fry: One Jillion dollars.
Read from file: [Everyone gasps.]
Read from file: Auctioneer: Sir, that's not a number.
Read from file: 数据读取, 测试 。

Read from file: Fry: One Jillion dollars.
Read from file: [Everyone gasps.]
Read from file: Auctioneer: Sir, that's not a number.
Read from file: 数据读取, 测试 。

Error opening  dataFUNNY.txt for input
Press any key to continue

转自:http://www.cnblogs.com/JCSU/articles/1190685.html

posted on 2011-07-30 21:46  COS  阅读(709)  评论(0编辑  收藏  举报