The C++ file input and output: using the write(), seekp(), tellp(), open(), close() member functions in C++ program

 

Compiler: Visual C++ Express Edition 2005

Compiled on Platform: Windows XP Pro SP2

Header file: Standard

Additional library: none/default

Additional project setting: Set project to be compiled as C++

Project -> your_project_name Properties -> Configuration Properties -> C/C++ -> Advanced -> Compiled As: Compiled as C++ Code (/TP)

Other info: none

To do: Using the write(), seekp(), tellp(), open(), close() member functions in C++ programming

To show: How to use the write(), seekp(), tellp(), open() and close() member functions in C++ programming

 

// using the seekp() and tellp() member functions

#include <iostream>

#include <fstream>

using namespace std;

 

void main(void)

{

// provide a full path if needed

char filename[ ] = "C:\\testfileio4.txt";

ofstream outputfile;

int locate;

 

// creating, opening and writing data to a file

outputfile.open(filename, ios::out);

 

// simple error handling for file creating/opening test if fail to open

if(outputfile.fail())

{

cout<<"Creating and opening "<<filename<<" file for writing\n";

cout<<"----------------------------------------------------\n";

cout<<"The "<<filename<<" file could not be created/opened!\n";

cout<<"Possible errors:\n";

cout<<"1. The file does not exist.\n";

cout<<"2. The path was not found.\n";

exit(1); // just exit

// 0-normal, non zero - some error

}

// if successful creating/opening the file

else

{

cout<<"The "<<filename<<" file was created and opened successfully!\n";

cout<<"\nDo some file writing....\n\n";

outputfile.write("Testing: Just simple example.", 29);

 

// tell the pointer position

locate = outputfile.tellp();

 

// seek the pointer position with offset

outputfile.seekp(locate-16);

 

// write for 7 length

outputfile.write(" rumble", 7);

// close the output file

outputfile.close();

 

// simple error handling for output files closing test if fail to close the file, do...

if(outputfile.fail())

{

cout<<"The "<<filename<<" file could not be closed!\n";

exit(1);

}

// if successful to close the file

else

cout<<"\nThe "<<filename<<" file was closed successfully!\n";

}

}

 

Output example:

 

The C:\testfileio4.txt file was created and opened successfully!

Do some file writing....

The C:\testfileio4.txt file was closed successfully!

Press any key to continue . . .

 

The testfileio4.txt file content is shown below.

 

 

Testing: Just rumble example.

 

 

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