ex25.c

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include "dbg.h"

#define MAX_DATA 100

int read_string(char** out_string, int max_buffer)
{
	*out_string = calloc(1, max_buffer +1);
	check_mem(*out_string);

	char* result = fgets(*out_string, max_buffer, stdin);
	check(result != NULL, "Input error");
	return 0;

error:

	if(*out_string) {
		free(out_string);}

	*out_string = NULL;
	return -1;
}

int read_int(int* out_int)
{
	char* input = NULL;
	int   rc = read_string(&input, MAX_DATA);
	check( rc == 0, "Failed to read number.");

	*out_int = atoi(input);
	free(input);
	return 0;

error:

	if (input) {
		free(input);}
	return -1;
}

int read_scan(const char* fmt, ...)
{
	int i  = 0;
	int rc = 0;
	int*   out_int  = NULL;
	char*  out_char = NULL;
	char** out_string = NULL;
	int max_buffer = 0;

	va_list argp;
	va_start(argp, fmt);

	for(i = 0; fmt[i] != '\0'; i++) {
		if( fmt[i] == '%') {
			i++;
			switch (fmt[i]) {
				case '\0':
					sentinel("Invalid format, ended with %%.");
					break;

				case 'd':
					out_int = va_arg(argp, int*);
					rc = read_int(out_int);
					check(rc == 0, "Failed to read int.");
					break;

				case 'c':
					out_char = va_arg(argp, char*);
					*out_char = fgetc(stdin);
					break;

				case 's':
					max_buffer = va_arg(argp, int);
					out_string = va_arg(argp, char**);
					rc = read_string(out_string, max_buffer);
					check(rc == 0, "Failed reading string.");
					break;

				default:
					sentinel("Invalid format");}}
		else {
			fgetc(stdin);}
		check(!feof(stdin) && !ferror(stdin), "Input error.");}

	va_end(argp);
	return 0;

error:

	va_end(argp);
	return -1;
}

int main(int argc, char* argv[])
{
	char* first_name = NULL;
	char  initial = ' ';
	char* last_name  = NULL;
	int age = 0;

    printf("What's your first name? ");
    int rc = read_scan("%s", MAX_DATA, &first_name);
    check(rc == 0, "Failed first name.");

    printf("What's your initial? ");
    rc = read_scan("%c\n", &initial);
    check(rc == 0, "Failed initial.");

    printf("What's your last name? ");
    rc = read_scan("%s", MAX_DATA, &last_name);
    check(rc == 0, "Failed last name.");

    printf("How old are you? ");
    rc = read_scan("%d", &age);

    printf("---- RESULTS ----\n");
    printf("First Name: %s", first_name);
    printf("Initial: '%c'\n", initial);
    printf("Last Name: %s", last_name);
    printf("Age: %d\n", age);

    free(first_name);
    free(last_name);
    return 0;
error:
    return -1;
}