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(shù)據(jù)讀取， 測試 。
以下就是基于 data.txt 的數(shù)據(jù)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(shù)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(shù)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(shù)據(jù)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(shù)據(jù)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(shù)據(jù)讀取， 測試 。
Error opening dataFUNNY.txt for input
Press any key to continue
posted on 2012-03-31 16:50
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