Experiment with interpolating strings

expand.c

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

int expand(char *target, int size, char *format, char **params, int count)
{
	int i, placeholders = 0;
	for (i = 0; i < strlen(format); i++) {
		if (format[i] == '?') {
			placeholders++;
		}
	}

	if (placeholders != count) {
		return 1;
	}

	int j = 0, k = 0;
	for (i = 0; i < strlen(format); i++) {
		if (format[i] == '?') {
			int len = strlen(params[k]);
			if (j + len > size) {
				break;
			}

			target[j] = 0;
			strcat(target, params[k]);
			j += strlen(params[k]);
			k++;
		} else {
			target[j] = format[i];
			j++;
		}
	}

	target[j] = 0;

	return 0;
}

int main(void)
{
	char *format = "FOO(?, ?, ?)";
	char target[1024];
	char *params[3] = { "emil", "hannes", "lydia" }; 

	expand(target, sizeof(target), format, params, 3);

	printf("%s\n", target);

	return 0;
}