Store a 'file' in 'pure c source code' as char*

Question

I need to store something in source as a char array so I can read it later,

how to store it in source file as char pointer and how to convert a binary file to char pointer?

I remember I saw some demo before that use this way to publish small demo without carry some small files, such as 5k or even 100k size of file.

oh, the "size of file" edit at the end of the post really made things clear now. — Mike Nakis, Dec 28 '11 at 14:08
If I understand correctly, you wish to embed binary data into your executable so that you don't need to supply it as a separate file? — Oliver Charlesworth, Dec 28 '11 at 14:10
yes that's it, I am using gcc and pure c, I think I need a way to convert a binary file to some sort of format and paste in as char *file1 ={paste stuff}; ??? — user1051003, Dec 28 '11 at 14:13
possible duplicate of ["#include" a text file in a C program as a char\[\]](http://stackoverflow.com/questions/410980/include-a-text-file-in-a-c-program-as-a-char). I also think [my answer](http://stackoverflow.com/questions/410980/include-a-text-file-in-a-c-program-as-a-char/411000#411000) fits. — Hasturkun, Dec 28 '11 at 14:44

score 2 · Answer 1 · answered Dec 28 '11 at 22:21

2

The xxd tool can do this:

xxd -i inputfile

answered Dec 28 '11 at 22:21

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score 0 · Accepted Answer · answered Dec 28 '11 at 14:19

I usually use a simple Perl/Ruby/Python script to convert binary data to C source code:

# Python script bin_to_c.py
import sys

i = 0
res = []
res.append("unsigned char data[] = \"")
for c in sys.stdin.read():
  if i % 15 == 0:
    res.append("\"\n    \"")
  res.append("\\x%02x" % ord(c))
  i += 1

print ''.join(res) + '";'
print "size_t data_size = sizeof(data) - 1;"

You can then paste the output into a C file, like this:

python bin_to_c.py < input.bin > data.c

score 0 · Answer 3 · answered Dec 28 '11 at 14:28

I'm not sure whether you want to open a binary file or binary mode.

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    FILE *fp = NULL;
    int len = 0;
    char * file_buff = NULL;

    if ((fp = fopen("file1", "rb")) == NULL) {
        printf("Failed to open file\n"); 
        return EXIT_FAILURE;
    }   

    fseek(fp, 0, SEEK_END);
    len = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    if ((file_buff = (char *) malloc((int)sizeof(char) * len)) == NULL) {
        printf("ERROR: unable to allocate memory\n");
        return EXIT_FAILURE;
    }   

    fread(file_buff, len, 1, fp);   
    fclose(fp);

    printf("Contents of the file : \n%s", file_buff);

    /* do whatever you wanted to do with file_buff here */

    /* once done, free the file buffer */
    free(file_buff);

    return EXIT_SUCCESS;
}

Store a 'file' in 'pure c source code' as char*

3 Answers3