Thread: Populating structure through a switch statement?

Hi,

Ok I've got two programs here. The first one is simply asking for an employee's name and age and storing them in an array of structures, then displaying them. Works fine, woop-de-do...

Code:

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

struct EMPLOYEE
{
	char name[45];
	int age;
};

void get_name (struct EMPLOYEE person []);
void disp_name (struct EMPLOYEE person []);

void main ()
{
	struct EMPLOYEE person [5];

	get_name (person , 5);
	disp_name (person , 5);
	getch ();
}
void get_name (struct EMPLOYEE person [])
{
	int i = 0;

	for (i = 0; i < 5; i ++)
	{
	printf ("Enter name: \n");
	gets (person[i].name);
	printf ("Enter age: \n");
	scanf ("%d" , &person[i].age);
	fflush (stdin);
	}
}
void disp_name (struct EMPLOYEE person [])
{
	int i = 0;

	for (i = 0; i < 5; i ++)
	{
	printf ("Name is: %s \n" ,person[i].name );
	printf ("Age is: %d \n" , person[i].age);
	}
}

Now the second program, which is just a more worked up version is giving me a headache. I've taken the above example and 'tried' to get some user selection into it. The problem is the loop in the get_name function just runs and runs. It's supposed to populate an array of 5 structures! I'm thinking it's something to do with the switch statement, not passing the structure correctly?. Any advice would be really appreciated at this point.

Code:

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

struct EMPLOYEE
{
	char name[45];
	int age;
};

int get_selection ();
void use_selection (int selection , struct EMPLOYEE person []);
void get_name (struct EMPLOYEE person []);
void disp_name (struct EMPLOYEE person []);

void main ()
{
	struct EMPLOYEE person [5];
	int selection = 0;

	selection = get_selection ();
	use_selection (selection ,  person);

	getch ();
}
int get_selection ()
{
	int selection = 0;

	printf ("*** Main menu ***\n");
	printf ("1.Add employee\n2.Display all employees\n3.Quit");
	printf ("Enter choice: ");

	do
	{
		scanf ("%d" , &selection);
		fflush (stdin);

		if ((selection < 1) || (selection > 5))
		{
			printf ("Invalid selection. Please re-enter: ");
		}
	}while((selection < 1) || (selection > 5));
	return (selection);
}
void use_selection (int selection , struct EMPLOYEE person[])
{
	do
	{
		switch (selection)
		{
		case 1 :
			get_name (person , 5);
			break;
		case 2 :
			disp_name (person , 5);
			break;
		case 3 :
			printf ("Exiting");
			break;
		}
		}while(selection != 3);
}
void get_name (struct EMPLOYEE person [])
{
	int i = 0;

	for (i = 0; i < 5; i ++)
	{
	printf ("Enter name: \n");
	gets (person[i].name);
	printf ("Enter age: \n");
	scanf ("%d" , &person[i].age);
	fflush (stdin);
	}
}
void disp_name (struct EMPLOYEE person [])
{
	int i = 0;

	for (i = 0; i < 5; i ++)
	{
	printf ("Name is: %s \n" ,person[i].name );
	printf ("Age is: %d \n" , person[i].age);
	}
}

It's because of do while loop in use_selection() function.

Indeed it was! Thanks for the help.

You should get an error here

Code:

			get_name (person , 5);

get_name doesn't have that many parameters.

Code:

void get_name (struct EMPLOYEE person []);

Also you should read this

Cprogramming.com FAQ > Why fflush(stdin) is wrong

I don't know how you actually been able to compile that. You defined your get_name function like this:

Code:

void get_name (struct EMPLOYEE person []);

but you call it like this:

Code:

get_name (person , 5);

Right, well following your suggestions I've tidied up the code a bit (yes gets will be tweaked too)

As for 'where did you learn this stuff?' - I'm a beginner with maybe 3 spare hrs a week to study. Thought I was doing ok for 6 weeks practice? I'm sure you didn't wake up one day and all the knowledge was just sat there fizzing in your grey matter Elysia.

And for my next annoying question... After populating the array of structures I return to the main menu (get_selection) function. My issue is the program terminates whatever the input. So say I enter 2 - display all employees, the program ends. Again, I cant pick out why this is happening. Any thoughts?

Code:

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

struct EMPLOYEE
{
	char name[20];
	int age;
};

int get_selection ();
void use_selection (int selection , struct EMPLOYEE person []);
void get_name (struct EMPLOYEE person []);
void disp_name (struct EMPLOYEE person []);

int main (void)
{
	struct EMPLOYEE person [5] = {"Enter name",0};
	int selection = 0;

	selection = get_selection ();
	use_selection (selection ,  person);

	
	return 0;
}
int get_selection ()
{
	int selection = 0;
	system ("cls");
	
	printf ("*** Main menu ***\n");
	printf ("1.Add employee\n2.Display all employees\n3.Quit\n");
	printf ("Enter choice: ");
	do
	{
		scanf_s ("%d" , &selection);
		fflush (stdin);

		if ((selection < 1) || (selection > 5))
		{
			printf ("Invalid selection. Please re-enter: ");
		}
	}while((selection < 1) || (selection > 5));
	return (selection);
}
void use_selection (int selection , struct EMPLOYEE person[])
{
		switch (selection)
		{
		case 1 :
			get_name (person);
			break;
		case 2 :
			disp_name (person);
			break;
		case 3 :
			printf ("Exiting");
			break;
		}
}
void get_name (struct EMPLOYEE person [])
{	
	int selection = 0;
	int i = 0;
	for (i = 0; i < 5; i++)
	{
		system("cls");
		printf ("Enter employee %d's name: \n" , i+1);
		do
		{
			gets (person[i].name);
			if (strlen (person[i].name)> 20)
			{
				printf ("Name entered is too long. Please re-enter: ");
			}
		}while (strlen (person[i].name)> 20);
			
		printf ("Enter employee %d's age: \n" , i+1);
		do
		{
			scanf_s ("%d" , &person[i].age);
			fflush (stdin);
			if ((person[i].age < 1) || (person[i].age > 70))
			{
				printf ("Invalid entry (Uk retiremnt age is 70) Please re-enter: ");
			}
		}while ((person[i].age < 1) || (person[i].age > 70));
	}
	 get_selection ();
}

void disp_name (struct EMPLOYEE person [])
{
	int i = 0;

	for (i = 0; i < 5; i ++)
	{
	printf ("Name is: %s \n" ,person[i].name );
	printf ("Age is: %d \n" , person[i].age);
	}
}

beyond the very dangerous gets();
or the use of fflush(stdin);
both really bad ideas

you should get errors on compiling this. scanf_s is an undefined reference. I think you ment to say scanf("%d",&selection); this is twice in the code once in get_selection the other in get_name

Code:

scanf_s ("%d" , &selection);
		fflush (stdin);

What compiler are you using???

I'm using visual studio 2010 - perhaps it's just very forgiving. Interesting you say that though. scanf gives the warning - warning C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead.
scanf_s doesn't hence it's use.

That explains alot. I kinda figured it might be VS. Your right that scanf can be dangerous, its because the input can exceed the size of the array it is being put into. MS added scanf_s so not all compilers will handle that.

That's why I started using fgets for most input.