libhexer

A small, simple C/C++ library for reading and writing arbitrary binary data in hexadecimal format.

Motivation

This library was motivated by working on an existing code base that made extensive use of hexadecimal to exchange binary data between programs. I was dismayed to see the source littered with code fragments like

for (i = 0; i < 8; i++) {
    if (i == 4)
        printf(" ");
    printf("%02X", id[i]);
}
printf(":");
for (i = 0; i < 64; i++) {
    if (i % 4 == 0)
        printf(" ");
    printf("%02X", data[i]);
}
print("\n");

throughout, sometimes with stupid bugs that were obviously due to copying-and-pasting and failing to make some minor but required modification.

Even worse, there was also code like

printf("%08X:", *(uint32_t *)&id[0]);
for (i = 0; i < 16; i++) {
    printf(" %08X", *(uint32_t)&data[i*4]);
}
print("\n");

resulting in ambiguous or erroneous endianess when trying to interpret the output.

I decided to implement a more readable, maintainable, and less error-prone approach. For example, the first block above can be replaced with

XOUT.GroupSize(4).GroupSeparator(' ');
printf("%s: %s\n", XTOSTR(id, 8), XTOSTR(data, 64));

to output hex in the format

xxxxxxxx xxxxxxxx: xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx ...

Usage

#include <libhexer/hexer.h>

// Output fixed-sized integers using default settings.
printf("%s", XUINT32(a));
printf("%s", XUINT40(b));

// Output SHA-256 digest using defaults.
printf("%s", XTOSTR(digest, 32));

using namespace libhexer;

// Create custom output object that uses upper-case letters,
// groups of four bytes, and a single space between groups.
auto xout = HexOut::New().SetLetterCase(HexOut::UPPER)
                         .SetGroupSize(4)
                         .SetGroupSeparator(' ');

// Output fixed-sized integers using custom settings.
std::cout << xout.UInt64(a) << std::endl;
fprintf(f, "%s", xout.UInt64(a).c_str());