Embedding Binary Data in C/C++ Code (xxd -i)

While the primary purpose of xxd is to create hexadecimal dumps, xxd -i takes it a step further by generating a C include file that contains the binary data as an array.

xxd -i [input file] > [output.c]

The generated output.c file includes an array with the binary data from hello.txt. For example, you might get something like this in output.c:

Output: xxd -i hello.txt

unsigned char hello_txt[] is an array of unsigned characters, which represents the binary data of hello.txt.
The array is initialized with a list of hexadecimal values enclosed within curly braces. Each hexadecimal value represents a byte of data, with the 0x prefix denoting a hexadecimal number. The values correspond to the ASCII codes of the characters in “hello.txt.”
unsigned int hello_txt_len is an additional variable that stores the length of the array. In this case, it’s set to 30, indicating that the array contains 30 bytes of data.

Now, you can easily use this array in your C or C++ code, making it convenient for embedding binary data, such as images or other resources, directly into your applications.

C program to utilize the output of xxd -i:

You can use the generated C code to display the text from hello.txt as follows:

#include &lt;stdio.h&gt;

// The generated data
unsigned char hello_txt[]
    = { 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x68,
        0x6f, 0x77, 0x20, 0x61, 0x72, 0x65, 0x20, 0x79,
        0x6f, 0x75, 0x3f, 0x0a, 0x49, 0x27, 0x6d, 0x20,
        0x66, 0x69, 0x6e, 0x65, 0x21, 0x0a };

unsigned int hello_txt_len = 30;

int main()
{
    // Print the content of hello.txt
    for (unsigned int i = 0; i &lt; hello_txt_len; i++) {
        putchar(hello_txt[i]);
    }

    return 0;
}

Output

Hello, how are you?
I'm fine!

This C code includes the generated data array hello_txt and its length hello_txt_len. The program iterates through the array and uses the putchar function to display the data, printing the original content of “hello.txt.”

xxd Command in Linux

xxd is a command-line tool that is primarily used for creating and analyzing hexadecimal dumps from files. It can also be used to reverse the process and convert a hexadecimal dump back into binary form. In this article, let’s uncover the practical applications of the “xxd” command in the Linux ecosystem.

xxd Command in Linux

What is a ‘hexadecimal dump’?
Installing xxd on Linux
Using xxd command:
Generating hexadecimal dumps
Converting hexadecimal dump to the original file
Formatting output of xxd
Different dump output styles
Embedding Binary Data in C/C++ Code (xxd -i)

Embedding Binary Data in C/C++ Code (xxd -i)

C program to utilize the output of xxd -i:

xxd Command in Linux

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