C++讀寫文本

 

// ReadOrWriteTextLine.cpp : 定義控制台應用程式的進入點。
//

#include "stdafx.h"
#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("C:\\data.txt"); 
    string s; 
    while( fin >> s )
    {   
        cout << "Read from file: " << s << endl; 
    }
}

//讀取方式: 逐行讀取, 將行讀入字元數組, 行之間用斷行符號換行區分
//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("C:\\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, 將行讀入字串, 行之間用斷行符號換行區分
//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("C:\\data.txt"); 
    string s; 
    while( getline(fin,s) )
    {   
        cout << "Read from file: " << s << endl;
    }
}

//帶錯誤偵測的讀取方式
//Simply evaluating an I/O object in a boolean context will return false
//if any errors have occurred
void ReadDataWithErrChecking()
{
    string filename = "C:\\dataFUNNY.txt"; 
    ifstream fin( filename.c_str()); 
    if( !fin )
    {  
        cout << "Error opening " << filename << " for input" << endl;  
       // exit(-1); 
    }
}

 

int _tmain(int argc, _TCHAR* argv[])
{
  ReadDataFromFileWBW(); //逐詞讀入字串
    OutPutAnEmptyLine(); //輸出空行

    ReadDataFromFileLBLIntoCharArray(); //逐詞讀入字元數組
    OutPutAnEmptyLine(); //輸出空行

    ReadDataFromFileLBLIntoString(); //逐詞讀入字串
    OutPutAnEmptyLine(); //輸出空行

  ReadDataWithErrChecking(); //帶檢測的讀取

 

   ofstream o_file;       
    //寫
    o_file.open(("C:\\data.txt", ios::out | ios::app | ios::binary);

    for (int i = 1; i <= 10; i++)
    {
         o_file << "第" << i << "行\n"; //將內容寫入到文字檔中
    }
    o_file.close();

   system("Pause");
}

/*

#include <iostream>;
#include <string>;

char fileName[] = "C:\\test.txt";
ifstream in(fileName);
string line;
while(getline(line, in)) {
    cout << line << endl;
}

*/