假設有一個叫 data.txt 的文件, 它包含以下內容:

Fry:?One?Jillion?dollars.
[Everyone?gasps.]
Auctioneer:?Sir,?that's?not?a?number.
數據讀取，?測試?。
以下就是基于 data.txt 的數據讀取操作:

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

using?namespace?std;

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

//讀取方式:?逐詞讀取,?詞之間用空格區(qū)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.?
void?ReadDataFromFileWBW()
{
????ifstream?fin("data.txt");??
????string?s;??
????while(?fin?>>?s?)?
????{????
????????cout?<<?"Read?from?file:?"?<<?s?<<?endl;??
????}
}

//讀取方式:?逐行讀取,?將行讀入字符數組,?行之間用回車換行區(qū)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;
????}
}

//讀取方式:?逐行讀取,?將行讀入字符串,?行之間用回車換行區(qū)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;?
????}
}

//帶錯誤檢測的讀取方式
//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();?//逐詞讀入字符串?
????OutPutAnEmptyLine();?//輸出空行

????ReadDataFromFileLBLIntoCharArray();?//逐詞讀入字符數組
????OutPutAnEmptyLine();?//輸出空行

????ReadDataFromFileLBLIntoString();?//逐詞讀入字符串
????OutPutAnEmptyLine();?//輸出空行

????ReadDataWithErrChecking();?//帶檢測的讀取
????return?0;
}
輸出結果為:
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: 數據讀取，
Read from file: 測試
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: 數據讀取， 測試 。

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: 數據讀取， 測試 。

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

轉載于:https://www.cnblogs.com/kevin2010_vip/archive/2010/02/03/1662853.html

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