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>



usingnamespacestd;



//输出空行

voidOutPutAnEmptyLine()

{

cout<<"\n";

}



//读取方式: 逐词读取, 词之间用空格区分

//read data from the file, Word By Word

//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.

voidReadDataFromFileWBW()

{

ifstream fin("data.txt");

strings;

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.

voidReadDataFromFileLBLIntoCharArray()

{

ifstream fin("data.txt");

constintLINE_LENGTH=100;

charstr[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

voidReadDataFromFileLBLIntoString()

{

ifstream fin("data.txt");

strings;

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

voidReadDataWithErrChecking()

{

stringfilename="dataFUNNY.txt";

ifstream fin( filename.c_str());

if(!fin )

{

cout<<"Error opening"<<filename<<"for input"<<endl;

exit(-1);

}

}



intmain()

{

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

return0;

}

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原文链接: https://www.cnblogs.com/kevin2010_vip/archive/2010/02/03/1662853.html

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