How to make a menu on C? DOS

[luisvalencia]

Hello,

Can somebody explain me how to make a menu in C?
The menu must call another functions and validate that I enter a valid key, when I hit enter in the other screen it must go back to the main menu

For example.
MAIN MENU
1. Sum
2. Rest
Press function to continue.

If I press 1. The whole screen must be blank and show me something like
Enter digit number 1:
Enter digit number 2:
The result is :

Press Enter to go the main menu.


Thanks for your help.

[nkhambal]

You can try this

int choice;

do 
{
 printf("Menu\n\n");
 printf("1. Sum\n");
 printf("2. Rest\n");
 printf("3. Exit\n");
 scanf("%d",&choice);
  
 switch (choice)
 {
     1: /*Call function here to do the required operation*/
          break;
     2: /*Call function here to do the required operation*/
          break;
     3: printf("Goodbye\n"); 
         break;
     default: printf("Wrong Choice. Enter again\n");
                    break;
 } 
 
} while (choice != 3);

[luisvalencia]

It seems to be easy but I get many errors.
Building main.obj.
C:\Archivos de programa\PellesC\Projects\3\main.c(5): warning #2027: Missing prototype for 'sum'.
C:\Archivos de programa\PellesC\Projects\3\main.c(10): error #2048: Undeclared identifier 'f12'.
C:\Archivos de programa\PellesC\Projects\3\main.c(13): error #2168: Operands of + have illegal types 'char *' and 'float'.
C:\Archivos de programa\PellesC\Projects\3\main.c(13): error #2140: Type error in argument 1 to 'printf'; found 'float' expected 'restrict const char *'.
C:\Archivos de programa\PellesC\Projects\3\main.c(21): warning #2027: Missing prototype for 'printmenu'.
C:\Archivos de programa\PellesC\Projects\3\main.c(26): warning #2027: Missing prototype for 'printmenu'.
C:\Archivos de programa\PellesC\Projects\3\main.c(26): error #2120: Redeclaration of 'printmenu' previously declared at C:\Archivos de programa\PellesC\Projects\3\main.c(21): found 'void __cdecl function(void)' expected 'int __cdecl function'.
C:\Archivos de programa\PellesC\Projects\3\main.c(38): error #2001: Syntax error; found ':' expecting ';'.
C:\Archivos de programa\PellesC\Projects\3\main.c(38): error #2061: Illegal statement termination.
C:\Archivos de programa\PellesC\Projects\3\main.c(39): warning #2154: Unreachable code.
C:\Archivos de programa\PellesC\Projects\3\main.c(41): error #2001: Syntax error; found ':' expecting ';'.
C:\Archivos de programa\PellesC\Projects\3\main.c(41): error #2061: Illegal statement termination.
C:\Archivos de programa\PellesC\Projects\3\main.c(43): error #2001: Syntax error; found ':' expecting ';'.
C:\Archivos de programa\PellesC\Projects\3\main.c(43): error #2061: Illegal statement termination.
C:\Archivos de programa\PellesC\Projects\3\main.c(44): warning #2154: Unreachable code.
*** Error code: 1 ***
Done.


#include <stdio.h>


void sum()
{
	float f1,f2;
	printf("Enter first number\n\n");
	 scanf("%f",&f1);
	printf("Enter second  number\n\n");
	scanf("%f",&f12);
	float total;
	total = f1 + f2;
	printf("The result is" + f1 +  f2);
	printf("Press key to go to the main menu\n\n");

	// Here it must detect the enter key and then go to the main menu
}

void main()
{
	printmenu();
}


void printmenu()
{
		int choice;
	do 
	{
		 printf("Menu\n\n");
		 printf("1. Sum\n");
		 printf("2. Rest\n");
		 printf("3. Exit\n");
		 scanf("%d",&choice);
  
		 switch (choice)
 		{
			1:
  		 	sum();
          		break;
     			2: /*Call function here to do the required operation*/
      			break;
     			3: 
			printf("Goodbye\n"); 
         		break;
    			default: printf("Wrong Choice. Enter again\n");
                    break;
 		}	 
 
	} while (choice != 3);
	
}



<code>
#include <stdio.h>


void sum()
{
	float f1,f2;
	printf("Enter first number\n\n");
	 scanf("%f",&f1);
	printf("Enter second  number\n\n");
	scanf("%f",&f12);
	float total;
	total = f1 + f2;
	printf("The result is" + f1 +  f2);
	printf("Press key to go to the main menu\n\n");

	// Here it must detect the enter key and then go to the main menu
}

void main()
{
	printmenu();
}


void printmenu()
{
		int choice;
	do 
	{
		 printf("Menu\n\n");
		 printf("1. Sum\n");
		 printf("2. Rest\n");
		 printf("3. Exit\n");
		 scanf("%d",&choice);
  
		 switch (choice)
 		{
			1:
  		 	sum();
          		break;
     			2: /*Call function here to do the required operation*/
      			break;
     			3: 
			printf("Goodbye\n"); 
         		break;
    			default: printf("Wrong Choice. Enter again\n");
                    break;
 		}	 
 
	} while (choice != 3);
	
}

[0rion]

You didn't use the switch statement correctly, it's meant to be something like this:

switch(choice)
{
        case 1: printf("You have entered choice 1\n");
                    break;
        case 2: printf("You have entered choice 2\n");
                    break;
        default: printf("Invalid choice!\n");
                    break;
}

And also don't use void main() use int main(void) or int main(int argc, char** argv) instead.

This might give you a better overview, you can add in error control if you need it.

#include <stdio.h>

void load_menu(void);
void sum(void);
void rest(void);

int main(int argc, char** argv)
{
	load_menu();
	return 0;
}

void load_menu(void)
{
	int choice;

	do 
	{
		printf("Menu\n\n");
		printf("1. Sum\n");
		printf("2. Rest\n");
		printf("3. Exit\n");
		scanf("%d",&choice);

		switch(choice)
		{
			case 1: sum();
				break;
			case 2: rest();
				break;
			case 3: printf("Quitting program!\n");
				exit(0);
				break;
			default: printf("Invalid choice!\n");
				break;
		}

	} while (choice != 3);

}

void sum(void)
{
	int num1, num2;
	int ch;
	
	printf("Enter number 1: ");
	scanf("%d",&num1);
	printf("Enter number 2: ");
	scanf("%d",&num2);

	printf("\nThe sum of the numbers was: %d",num1+num2);

	/* Flushes input buffer from the newline from scanf() */
	while ( (ch = getchar()) != '\n' && ch != EOF) ;

	printf("\n\nPress ENTER to continue.");
	while ( (ch = getchar()) != '\n' && ch != EOF)
		;

	return;
}		

void rest(void)
{
	int ch;
	printf("Sleepy sleepy... zZZzZzZz\n");
	printf("You now feel awake again!\n");

	/* Flushes input buffer */	
	while ((ch = getchar()) != '\n' && ch != EOF) ;

	printf("\n\nPress ENTER to continue.");
	while ((ch = getchar()) != '\n' && ch != EOF)
		;

	return;
}

[luisvalencia]

Thank you very much. Its working now.

A last question is How Can I Erase the whole screen and if its an easy way to make a menu centered=??


I would do it as

*********************
* MENU *
* 1. sUM *
*********************

And is it possible to color the characters or the menu in DOS? I want to HIGHLIGHT the * chars and the MENU TITLE

Thanks.

[nkhambal]

A last question is How Can I Erase the whole screen

If you are working on Windows, then you can use clrscr() function in conio.h.

If on unix platform the use "system("clear")" to clear the screen.

For all other questions, you are looking at graphics programmming. If on Windows you can look into the BGI graphics library which is supplied with Borland C compiler. If on Unix, "ncurses" is the solution.

[quzah]

Of course you could always just read the FAQ too...

Quzah.

[sand_man]

I'm sure he is grateful that someone did his homework for him.

[luisvalencia]

I dont understand the last part you gave me.


How should I use that on my program?

[quzah]

Oh, I don't know. Perhaps the FAQ will tell you. Don't you even understand basic logic? Where do you think you'd put something to potentially clear the screen? Hey, I know, how about some place in your program where you want it to clear the screen!


Quzah.

[luisvalencia]

I alredy included conio.h and I got this
C:\Archivos de programa\PellesC\Projects\3\main.c(14): warning #2027: Missing prototype for 'clrscr'.
C:\Archivos de programa\PellesC\Projects\3\main.c(58): warning #2027: Missing prototype for 'exit'.

[quzah]

1) Looks like you don't have clrscr in your conio.h.
2) exit is not prototypes in conio.h, it's in stdlib.h.

This is why you either need to take a moment to look things up on your own (ie: You'd be done by now, instead of waiting for some one to answer you.), and/or have a good reference book around (and use it).

Quzah.

[luisvalencia]

If I dont have clrscr in my conio.h what should I do?

[luisvalencia]

. I am having problems using Borland specific functions such as clrscr()

Include conio.h to your source, and add C:\Dev-C++\Lib\conio.o to "Further Object Files" in Project Options (where C:\Dev-C++ is where you installed Dev-C++)


I did this as in the FAQ but there is no conio.o

[Dave_Sinkula]

Since Pelles C is not Dev-C++, why not try some of the other methods mentioned in the FAQ?