C If Loop Fails to Set Struct Data - c

Question

This has stumped me for a few days now. I have tried searching but have turned up mostly just definitions for struct...
In an if loop I set 2 struct variables, but neither of them come out correct. guests[x].plusone is stuck at 0 and guests[x].plusonefood is simply empty. If I set them (with the same line) outside of the loop, however, there are no issues. My compiler shows no warnings or errors. What am I missing?
This is my first project with C, so please point out anything else you notice, too.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct guestinfo
{
char name[50];
short int plusone;
char food[50];
char plusonefood[50];
};
char temp[5];
char setfood (int f)
{
char foodtemp[f];
int x;
for (x=0; x < f; x++)
{
printf("Food option %d:\n", (x+1));
fgets(&foodtemp[x],100,stdin);
}
return *foodtemp;
}
int main ()
{
int number_of_rsvp=0;
int number_of_food=0;
printf("Number of food choices:\n");
fgets(temp,5,stdin);
number_of_food = atoi (temp);
while (number_of_food <= 0)
{
printf("Please enter a number greater than 0\n");
fgets(temp,5,stdin);
number_of_food = atoi (temp);
}
char food [50] [number_of_food];
**food = setfood(number_of_food);
printf("Number of RSVPs:\n");
fgets(temp,5,stdin);
number_of_rsvp = atoi (temp);
while (number_of_rsvp <= 0)
{
printf("\nPlease enter a number greater than 0\n");
fgets(temp,5,stdin);
number_of_rsvp = atoi (temp);
};
struct guestinfo guests[number_of_rsvp];
int x;
int f;
for (x=0; x < number_of_rsvp; x++)
{
// add input validation to this section
printf("Guest Number %d:\n\nGuest Name:\n", (x+1));
fgets(guests[x].name,50,stdin);
printf("Food Choice #:\n");
fgets(temp,3,stdin);
f = atoi(temp);
f--;
*guests[x].food = food [50] [f];
printf("Plus One? Y/N\n");
fgets(temp,3,stdin);
}
if (strchr (temp,'Y') != NULL || strchr (temp,'y') != NULL) //This loop
{
guests[x].plusone = 1;
printf("Plus one food choice #:\n");
fgets(temp,3,stdin);
f = atoi(temp);
f--;
*guests[x].plusonefood = food [50] [f];
}
else if (strchr (temp,'N') != NULL || strchr (temp,'n') != NULL)
{
guests[x].plusone = 0;
};
FILE *guestlist = fopen ("guestlist.txt","w");
// debugging
printf("%d\n",guests[0].plusone);
printf("%s\n",guests[0].plusonefood);
for (x=0; x < number_of_rsvp; x++)
{
fprintf(guestlist,"Guest Number %d:\n\nName: %s\nFood Choice: %s\n",(x+1),guests[x].name,guests[x].food);
switch (guests[x].plusone)
{
case 1:
{
fprintf(guestlist,"Plus One: Yes\n\tPlus One Food: %s\n\n",guests[x].plusonefood);
break;
}
case 0:
{
fprintf(guestlist,"Plus One: No\n\n");
break;
}
default:
{
break;
}
}
}
fclose (guestlist);
printf("Printing Guest List...\n");
return 0;
}

Answer 1

The problem is that you are accessing an invalid memory place.
The array has number_of_rsvp elements.
Your for() loop interates over the variable x up to the value number_of_rsvp and exits.
After that, the value of x is equal to number_of_rsvp.
Since the index of the array only can go from 0 to number_of_rsvp - 1, the element guests[x], which is guests[number_of_rsvp], is out-of-bound.