What is a binary file, how to open it?

Table of Contents

Binary file

What is a Binary file?

A binary file is a computer file that is different form a text file. It may contain data, like a computer program, or it may be a file that stores data for a program to use. In generally, it is a machine code, compilated by the assembly language.

how to open binary file?

There are a few different ways to open a binary file. The common way is to use the Binary Editor: C++ or Windows API function.

1.bin file Editor: C++ Programm

To open a binary file with C++, you need to use the ifstream class, which is part of the standard C++ library. To use this method, you first need to include the fstream header file. Then, you can open a binary file by using the ifstream::open() member function, passing in the name or path of the file as a parameter. For example:

1.1 Open bin file

/// C++ open bin file
void getBinSize(std::string path)
int size = 0;
std::ifstream infile(path, std::ifstream::binary);

infile.seekg(0, infile.end);
int size= infile.tellg();
infile.seekg(0, infile.beg);

printf("\npath=%s,size=%d \n", path, size);
return size;

void readBin(std::string path, char *buf, int size)
std::ifstream infile(path, std::ifstream::binary);

infile.read(static_cast<char *>(buf), size);

1.2 Saving Bin File

/// C++ save bin file
void writeBin ( std::string path , char * buf , int size )
{ std::ofstream outfile ( path , std::ifstream::binary );

outfile.write((char *)(buf), size);


1.3 Reading Bin File

// read binFile
std::string filePath= "./demo.bin";
int size = GetBinSize(filePath);
char *buf= new char[size];
readBin(filePath, buf, size);
float *fbuf = reinterpret_cast<float *>(buf);

// write binFile
std::string saveFilePath= "./demo_saved.bin";
writeBin(saveFilePath, buf, size);

delete buf;

2. Windows API function CreateFile()

Another way to open a binary file is to use the Windows API function CreateFile(). This function is part of the Windows API, which is not part of the C++ standard library. However, you can use it in your C++ programs by including the Windows.h header file. The CreateFile() function takes a variety of parameters, but the most important ones for opening a binary file are the file name or path, the desired access (for example, GENERIC_READ for reading or GENERIC_WRITE for writing), and the share mode (for example, FILE_SHARE_READ to allow other processes to read the file while your process has it open). For example:

#include Windows.h>

int main()
// ...



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Aidan Taylor
Aidan Taylor

I am Aidan Taylor and I have over 10 years of experience in the field of PCB Reverse Engineering, PCB design and IC Unlock.

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