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How to read binary files in C++

January 21, 20249 min read

In this article, we will learn how to read binary file in C++. The concept of reading a binary file means reading the raw bytes of the file rather than the data inside the file. In C++, there are many methods and methods through which we can read any type of file like binary files, text files, PDF files and many more. This programming language uses streams for file processing to achieve these tasks. Here, we will learn about reading operations of binary files using stream-based library. We will learn how to read binary file with appropriate examples.

What is binary file in C++?

Binary file is a file in C++ that always stores data that is not in a format easily understandable to humans. Only computers read binary data; Binary means data in the sequence of “0,1” or ASCII format. It contains encrypted data. Humans cannot understand this type of file, and only computers can work with this type of binary file. The elementary operator in C++ reads raw binary data and handles the data at the binary level. Therefore, these file manipulations are too complex for humans. Dealing with this type of file is a complex or complicated task in the programming world.

Standard library used to read binary file in C++ Main There are file stream classes like “ifstream” and “ofstream” from the stream header. We use “ifstream” library to read the binary file. We open the binary file using the flag which is “ios::binary”. It is necessary to open the binary file to ensure that the data is read in its binary format. Handling binary files requires very careful consideration of data types and file structures.

Importance of binary file in C++

Binary file plays a vital role in handling file processing in C++. Binary file requires a critical approach to achieve proper storage of data and their retrieval. Binary files facilitate us in the programming world in various ways:

data integrity

Binary files store data or information byte by byte without any formatting and additional interpretation. It also removes the risk of a sudden data corruption incident. The integrity of binary files is maintained in this proper manner.

more efficient

Binary files are more efficient and valuable in terms of file storage. The data in this file is in numeric storage such as IEEE or 5765, rather than long letters or text. The data is in encrypted form, so the speed of this file is faster and more efficient to handle the required data.


Due to the stability and accessible understanding of binary data representation, users are encouraged to use binary files for compatibility across different environment platforms and programming languages.

In which scenario should we read binary files?

Let us take a quick example to learn about the operation of reading binary files in appropriate programs. These examples help us explore more emerging techniques for handling binary files in the C++ programming language.

Scenario 1: Read binary files using read() function with ifstream

In C++, we can read binary files using streams and various methods to store or transfer data to different locations. In this scenario, we will learn to easily read binary file in C++ by just calling “if” stream and “read” function with the help of standard libraries. The code snippet of this scenario is mentioned in the following for better understanding:

int main,, ,
std::ifstream file,“binarydata.bin”std::ios::binary,,
If ,,,, ,
four buffers[200], ,Buffer is used to store temporary data,buffer, size,buffer,,,
std::cout,“File opened successfully”,
, Other ,
std::cout , “unable to open file”,
return 0,

In this code snippet, we open a binary file that is already created in our system, and the text data is stored there. Binary files contain encrypted data, so visualization of this type of data is challenging. After declaring valid utilities or libraries, we use stream file handling in the main function using the method “std::ifstream file()”. We pass “the address of the file that needs to be read” and “the type of the file in binary format std::ios:binary” to this file function.

After that, we apply the condition if the file address and format are correct. Then, we open the file. Otherwise, we show the error on the console window. Make sure that the given file exists in your system, and that the address is correct. Finally, run the code, and a console window containing the output will open.

The output screen shows that the binary file has been opened and the contents read. The content can be displayed on the screen as the data is not in text format.

Scenario 2: Read binary file using read() method

In this scenario, we will learn how to read binary file data using the read() method. The read() function reads data from files in blocks from the stream. We use another way to open a binary file by using the “file” pointer. Let's take an example of this scenario with the appropriate code snippet attached as follows:

int main,, ,
file ,file = fopen,“binarydata.bin”, “rb”,,
If ,file ,= zero, ,
char buffer_arr[100],
Fear,buffer_arr, sizeof,Four,size of,buffer_arr,, file,,
std::cout,“Read successfully…Binary file read via fread()”,
, Other ,
std::cout,,“unable to open file”,,
return 0,

Here, we And Add libraries like .js which are required for file stream and output purposes. In the main function, open a file using “fopen()” method and pass the binary file address with “.bin” extension and read mode. Initialize fopen() to a “file” pointer as we know the pointer stores data in a buffer. After this check whether the file is open or not. If file is not null, we read the file using fread(). Otherwise, we show the error that the file is not open. We compile this code in your Dev C++ environment and produce the result on the following console screen:

The given output screenshot shows that the file has been opened and read successfully.


In conclusion, we can say that binary files are complex files that are not understandable to humans, and the data inside these files is also encrypted and not in visible format. Here, we discussed the “Read” mode of binary files in detail. Remember that binary files must have the extension “.bin”, and the methods for reading the binary file must be valid and defined. Here, we have mentioned some of the best examples to understand the concept more clearly and concisely. Practice these code snippets in your environment to better understand the key concepts.

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