dbg.h: Quick and dirty print debugging

dbg.h is a header-only library for quick and dirty print debugging. It contains two macros inspired by Rust's dbg! macro: dbg() and dbgfmt().

These macros are intentionally simple and are meant as a debugging aid. They probably shouldn't hang around in your code for a long time outside of tests and the like. Find a real logging library if you need more featureful logging.

Requirements

• A complier that supports C11 or later

Macros

dbg()

dbg() works just about the same way as dbg!. It takes an expression and prints the result to stderr with the file name and source line.

dbg(1 + 1); // prints: [dbg] main.c:1: 1 + 1 = 2

dbg() also returns the result of the expression, so it can be put in the middle of just about any other expression.

int a = 2;
int b = dbg(a * 2) + 1; // prints: [dbg] main.c:1: a * 2 = 4

dbgfmt()

dbgfmt() works in the same way as dbg() except that you can choose the format specifier to print the result with.

// since wchar_t is just a typedef for some kind of integer type,
// you need to specify the `%lc` format if you want to display the
// character instead of the numerical value
wchar_t wc = L'a';

dbg(wc); // prints: [dbg] main.c:6: wc = 97
dbgfmt(wc, L'%lc'); // prints: [dbg] main.c:7: wc = L'a'

// control float precision
dbgfmt(0.1 * 0.2, %.2f); // prints [dbg] main.c:10: 0.1 * 0.2 = 0.02

// display numbers in hexadecimal
dbgfmt(127, 0x%x); // prints [dbg] main.c:13: 127 = 0x7f

// print and capture a result
int i = dbgfmt(0xdeadbeef + 0x10, %x); // prints [dbg] main.c:16: 0xdeadbeef + 0x10 = deadbeff