C + + read-write TXT file __c++

This article mainly introduces: C + + use Ifstream and ofstream function to read and write TXT file, including matrix and string reading and writing.

Description

The header files that need to be added are: #include <sstream>

#include <iostream>

#include <fstream>

#include <string>

You also need to add namespaces: using namespace std;

First, read the matrix

Sometimes the TXT store is a matrix element, and if the matrix element is spaced between spaces, it can be read with the following program:

	Ifstream infile;//define file variable
	infile.open (txtpath,ios::in);//Open Txtpath as file path
	if (!infile)
	{
		AfxMessageBox ("Failed to read TXT file.") ");
		return FALSE;
	}
	String temp,temp2mat;//defines an intermediate variable
	
	while (Getline (infile,temp))//reads a row, while loop, until the last line of the file
	{
		Istringstream Lineband (temp);//convert to data stream
		
		while (Lineband>>temp2mat)///sequentially output a number to Temp2mat until the last number of the line
		{
			int Value = Atoi (Temp2mat.data ());//convert Temp2mat from character to Integer, if floating-point number, atoi to Atof
			
		}
	}
	
	infile.close ();//Close file

Second, output matrix

	Ofstream outfile;//define file variable
	outfile.open (outpath,ios::out);//create file, outpath Create txt path
	if (!outfile)
	{
		AfxMessageBox ("Create TXT file failed.) ");
		return FALSE;
	}
	
	for (i=0;i<linenum;i++)/write each line sequentially, linenum the number of rows to write
	{
		for (j=0;j<rownum;j++)/write numbers in sequence, separated by spaces, RowNum the number of digits in the row
			outfile<<x<< ""; Write a number of space intervals x
			
		outfile<< "\ n";//write line newline
	}

	Outfile.close ()//close file

Note : Sometimes it is possible to write the last time after writing, and then only need to modify the type of open file: Outfile.open (outpath,ios::out | ios::app); Ios::app append at end of file

Related other types can be referred to blog: http://www.cnblogs.com/zhcncn/archive/2013/01/08/2851656.html

Third, read the string

You can read a string or a Chinese character.

	Ifstream infile; Definition file
	infile.open (inpath,ios::in);//inpath txt path
	if (!infile)
	{
		AfxMessageBox ("read feature file failed.") ");
		return;
	}
	string temp;
	Char str[64]; 
	CString str2;
	while (Getline (infile,temp))//reads a row sequentially until the file ends
	{
		memset (str, ' + ', sizeof (str));//read result to char*
		type memcpy (Str,temp.c_str (), temp.size ());

		STR2 = Temp.c_str ();  The read result is assigned to the CString type
	}

	infile.close ();//Close file

Iv. Writing strings

	Ofstream outfile;//define file variable
	outfile.open (inpath,ios::out);//create file, outpath Create txt path
	if (!outfile)
	{
		AfxMessageBox ("Create TXT file failed.) ");
		return;
	}
	int linenum = 1; Write number of rows
	char str[] = "txt";
	CString str2 = "Hello";
	for (int i=0;i<linenum;i++)/write each line sequentially, linenum the number of rows to write
	{
		outfile<<str;
		outfile<< "\ n"; Write str string

		outfile<<str2;
		outfile<< "\ n"; Write CString string
	}

	Outfile.close ()//close file