named_args.c

#include <stdio.h>
#include <stdbool.h>

struct _named_t {
	int arg1;
	int arg2;
	bool subtract_one;
};

int _calculate_sum(struct _named_t *args) {
	int result = args->arg1 + args->arg2;
	return args->subtract_one ? result - 1 : result;
}

#define calculate_sum(...) _calculate_sum(&(struct _named_t){ __VA_ARGS__ })

int main() {
	int result;
	// No surprise here
	result = calculate_sum( 3, 4 );
	printf( "%d\n", result ); // prints 7

	// We can explicitly name arguments
	result = calculate_sum( .arg1 = 3, .arg2 = 4 );
	printf( "%d\n", result ); // prints 7

	// When we name arguments, we can also give them in
	// an arbitrary order
	result = calculate_sum( .arg2 = 4, .arg1 = 3 );
	printf( "%d\n", result ); // prints 7

	// Also, we can add optional named arguments
	result = calculate_sum( 3, 4, .subtract_one = true );
	printf( "%d\n", result ); // prints 6

	return 0;
}