Thread: Beginner in C first menu - need critique

Hi, I am very new to C programing and am practicing functions, loops, and user input. So I decided a good way to mix all of that is to make a simple menu. I had a lot of trouble learning how to get user input without a mistake by the user crashing my program. I think I have a good solution my question is this: Is the solution I have come up with a good one? Am I making noob type mistakes here? If so is there any reference material that would help me understand my short comings in this area.

Here is my menu program.

Code:

/*Loop practice Making a menu
This is a simple menu that allows
three choices of destination and
quits when the user hits q
*/

#include <stdio.h>

/* Function templates */
void functone (void);
void functtwo (void);
void functthree (void);


int main ()
{
	// set up conditions for the loop
	
	int choice;
	char ch;
	choice = 0;
	
	// I used a do while loop to insure that it would run once
	do{
		// print menu
		printf ( "Make your choice.\n");
		printf ( "1 - 1st  program\n" );
		printf ( "2 - 2nd program\n" );
		printf ( "3 - 3rd  program\n" );
		printf ( "q to quit\n");
		
		// get user input and clear out stdin
		choice = getchar ();
		
                // this part clears the stdin of leftovers
		ch = getchar ();
		while ( ch != '\n' ) ch = getchar ();
		
		// Call the desired function
		if (choice == 49 ) {
			functone ();
		}
		if (choice == 50 ) {
			functtwo ();
		}
		if (choice == 51 ) {
			functthree ();
		}
	}
	// Check for escape code
	while ( choice != 113);
	
	// just to verify I finished
	printf ( "Done\n");
		
		return 0;
		
}

// The first called function on the menu
void functone (void)
{
	printf ( "You chose one\n");
}

// The second called function on the menu
void functtwo (void)
{
	printf ( "You chose two\n");
}

// The third called function on the menu
void functthree (void)
{
	printf ( "You chose three\n");
}

Thank you for the advice I have modified the program with your suggestions. I also made a new template for my IDE it was defaulting with the int main (). So I redid it to int main (void).

Here is the revised program.

Code:

/*Loop practice Making a menu
This is a simple menu that allows
three choices of destination and
quits when the user hits q
*/

#include <stdio.h>

/* Function templates */
void functone (void);
void functtwo (void);
void functthree (void);


int main (void)
{
	// set up conditions for the loop
	
	int choice;
	choice = 0;
	
	// I used a do while loop to insure that it would run once
	do{
		// print menu
		printf ( "Make your choice.\n");
		printf ( "1 - 1st  program\n" );
		printf ( "2 - 2nd program\n" );
		printf ( "3 - 3rd  program\n" );
		printf ( "q to quit\n");
		
		// get user input and clear out stdin
		choice = getchar ();
		// this part clears the stdin of leftovers
		while ( getchar() != '\n' ) ;
		
		// Call the desired function
		if (choice == '1' ) {
			functone ();
		}
		if (choice == '2' ) {
			functtwo ();
		}
		if (choice == '3' ) {
			functthree ();
		}
	}
	// Check for escape code
	while ( choice != 'q');
	
	// just to verify I finished
	printf ( "Done\n");
		
		return 0;
		
}

// The first called function on the menu
void functone (void)
{
	printf ( "You chose one\n");
}

// The second called function on the menu
void functtwo (void)
{
	printf ( "You chose two\n");
}

// The third called function on the menu
void functthree (void)
{
	printf ( "You chose three\n");

jimtuv, one thing is that you don't need to use the single quote( ' ) in your case statement, as you are dealing with integers. When you are using characters then you need to use the single quotes. For example

In case of using Integer

Code:

int choice;
...
...
switch (choice)
{
    case 1: printf("I am 1\n"); break;
    case 10: printf("I am 10\n"); break;
    default: printf("I am other than 1 and 10\n"); break;
}

In case of using Character

Code:

char choice;
...
...
switch (choice)
{
    case 'a': printf("I am A\n"); break;
    default: printf("I am other than A\n"); break;
}

jimtuv, what you had is correct only i didn't noticed that part in your code.

No problem cablu I am sure grateful you took the time to look at my code. Every input is helpful.

I decided to understand how the menu works that it would be good to try it out in a simple guessing game. In this game the computer picks a random number in a given range and allow a certain number of guesses for the user to find the answer.

Here the menu allows the user to input the desired difficulty and then run the game function. I know the input function is not right yet but I am not far enough along in my studies to make bullet proof input yet. I want to understand each function before going to much further.

I purposely broke it down in as many functions as I could to get practice in setting up and calling functions.

I have compile and run it and it seems to work as I would expect. Here is the Menu in the game.

It's amazing how small the main function is.

Code:

/* A guessing game from James Tuvell

In this game the computer picks a random number in
a certain range and the user will have a specified number
of tries to find that number

*/

#include <stdio.h>
#include <time.h>

int Menu (void);
void Instructions (int lownumb, int highnumb, int guesses );
int MenuInput (void);
int GameInput (void);
int Randnumb ( int lownumb, int highnumb );
void Game ( int lownumb, int highnumb, int guesses );

int main (void){
	
	// declare and initialize variables
	int answer;
		
	// main program loop
	do {
		// jump to menu
		
		answer = Menu ();
				
		/* On the menu selection jump to the Game function
			with the apropriate settings for that game
			difficulty.
		*/
		switch (answer){
			case '1' : Game ( 1, 20, 5); break;
			case '2' : Game ( 1, 50, 10); break;
			case '3' : Game ( 1, 99, 20); break;
		}
			
		
	}
	while ( answer != 'q' );
	
	return 0;
}

/* This is the menu function it only prints
*   the menu. It returns no value 
*/
int Menu (void){
	// menu function
	int answer;
	int numb;
	
	printf ( "\n\n" );
	printf ( "Chose you level of dificulty \n");
	printf ( "1 - Easy between 1 and 20 with 5 guesses\n");
	printf ( "2 - Medium between 1 and 50 with 10 guesses\n");
	printf ( "3 - Hard between 1 to 99 with 20 guesses\n");
	printf ( "q -to quit\n\n");
	
	answer = MenuInput ();
	return answer;
	
}

/* This prints the instructions for the game 
	based on the choice made from the menu
*/
void Instructions ( int lownumb, int highnumb, int guesses ){
	// print instruction for game
	
	printf ( "\n" );
	printf ( "I will think of a number " );
	printf ( "between %d and %d\n", lownumb, highnumb );
	printf ( "you have %d guesses to find it.\n\n", guesses );
	

}

/* This gets user input and returns the answer
*  it also will clear out the stdin buffer before
*  returning
*/
int MenuInput (void){
	
	int answer;
		
	answer = getchar ();
		
	while ( getchar () != '\n' );
	
	
	return answer;
}

/* This is the input for the game
	I still need to check for errors
	Have to add something to keep 
	letters from dumping my buffer
*/

int GameInput (void){
	
	int answer;
	
	scanf ( "%d", &answer );
	while ( getchar () != '\n' );
	
	return answer;
	
}

/* This is the random number generator that gets
	a range from the user and generates a random
	number in that range. It uses the time to initialize
	to prevent duplicate numbers
*/

int Randnumb ( int lownumb, int highnumb ){
	
	int randnumb;
	
	// initialize random number generator
	srand ( time (NULL) );
	
	randnumb = ( rand () % ( highnumb-lownumb ) + lownumb) ;
	
	return randnumb;
}

/* This function is the game function. It takes in the range
	of the number to be guessed and the number of  guesses
	that the user is alowed.
*/

void Game ( int lownumb, int highnumb, int guesses ){
	
	// declare variables
	int numb_to_guess;
	int guess;
	int digit;
	int i;
	
	// print instructions 
	Instructions ( lownumb , highnumb, guesses );
	
	// chose a number for user to guess
	numb_to_guess = Randnumb ( lownumb, highnumb );
	
	// Set the number of digits for user input
	digit = 2;
	
	// Main game loop
	for ( i = 0 ; i < guesses ; i++) {
		
		printf ( "Enter your guess:");
		guess = GameInput ( );
		
		if ( guess > numb_to_guess ){
			printf ( "Your too high try again!\n" );
		}
		if ( guess < numb_to_guess ) {
			printf ( "Your too low try again!\n");
		}
		if (guess == numb_to_guess ) {
			printf ( "You Win!!!\n");
			return;
		}
		
	}
	
	printf ("You loose!!! it was %d\n",numb_to_guess);
		
}