Thread: Menu driven program & filling an array - assistance needed

So I'm a bit stuck trying to figure out how to fill an array with a set of random number but not to print it out until the user requests to.

I've figured out how to create the random numbers and print them out.

And I'm using switch cases for my menu but not quite sure how to keep from the program ending and to allow still for the user to input until they decide to exit.

Code:

// This program will write a menu-driven program that allows the user to:// fill an array, query the array, and print the array.


#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 50


int main(){
    int range;
    int i;
    char choice;
    int array[SIZE];
// Array elements will range from 1-999
    srand (time(NULL));
    range = rand() % (999 - 1) +1;
    
    
    printf("******MENU******\n");
    printf("F. Fill the array with a random number series.\n");
    printf("P. Print the array.\n");
    printf("Q. Query the array.\n");
    printf("Z. Terminate the program.\n");
    printf("\n");
    printf("Select one of the following options:\n");
    
    scanf("%c", &choice);
    
    switch(choice){
    
        case 'F' : case 'f':
            printf("Please wait while the array is being filled...\n");
            printf("Process is complete.\n");
            break;
        
        case 'P' : case 'p':
            for(i = 0; i < SIZE; i++){
                printf("%i ", rand() %(999 - 1) +1);}
        break;

        case 'Q' : case 'q':
            printf("Please enter element you would like to query:\n");
        
        case 'Z' : case 'z':
        printf("Goodbye.");
        return(0);
        break;
        
        default:
            printf("Please select from the menu\n");
        }


}

For example, you enter F and then closes out versus letting you then enter p.
But mostly the issue is filling the array without printing until prompted.

In case 'P', is where I was able to create the array.

Suggestions would be awesome! I'm still pretty new to C though

Whenever you want any code to repeat (e.g. a menu and its execution), it needs to be in a loop -> For, While and Do While Loops in C - Cprogramming.com

For menus, a "do-while" loop is a good choice since it executes at least once before checking for the terminating condition.

Your "case F" is not filling an array.

Your "case P" is not printing an array - it is just printing out randomly generated numbers.

I'd suggest developing each of these separately, one at a time.

First, make your P option just print out the values of the array. That it is. You might want to initialize your array to all zeroes so it prints practical values (especially if the user starts by entering 'P' before 'F'). "int array[SIZE] = {0}" will initialize all elements to zero.

When that works, start working on your F option. There is no printing of values in that case, but instead generating random numbers and assigning them to your array.

Put the switch statement into label a
EDIT: For novice users, goto loop will be easier.

But if you intend to be professional programmer, avoid using goto loops, they form a "spaghetti" code.
You will be doing while() loop instead.

EDIT: For novice users, goto loop will be easier.

What do you mean by easier? Easier to learn bad practices.

But if you intend to be professional programmer, avoid using goto loops,

Avoid using goto loops even if you don't intend to be a professional programmer. They are considered a very bad practice and should be avoided by all novice programmers and most professional programmers. In very very knowledgeable hands they do have there use in extremely rare cases.


Jim

Not really. They are nicely used if you want to loop large code. Putting that in a while loop for example, causes scope confusions and loop-body addlement as well as loop-condition addlement.

Not really. They are nicely used if you want to loop large code.

Bull. Use one of the more accepted loop constructs, such as while(), do/while(), or for(). It is too easy to step out of a current scope into a different scope when using goto.

Putting that in a while loop for example, causes scope confusions and loop-body addlement as well as loop-condition addlement.

The proper use of functions and indentation should eliminate, or greatly reduce scope confusions. IMO if you have more than three levels of indentation you have too many and you need to see about reducing the complexity of that function.

Jim

@Matticus-

Thats the part im confused about. In my original code, those "random" numbers you say are being printed out are what I want to be my array that case 'F' fills with.
So to explain, what prints out from 'P' I want to be my array.


I've added the do/while loop, but its not correct. If I press: f, p or q it gives me the menu still regardless.

Code:

// This program will write a menu-driven program that allows the user to:
// fill an array, query the array, and print the array.


#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 50


int main(){
    int range;
    int i;
    char choice;
    char Z, z;
    int array[SIZE];
// Array elements will range from 1-999
    srand (time(NULL));
    range = rand() % (999 - 1) +1;
    
    do{
    printf("******MENU******\n");
    printf("F. Fill the array with a random number series.\n");
    printf("P. Print the array.\n");
    printf("Q. Query the array.\n");
    printf("Z. Terminate the program.\n");
    printf("\n");
    printf("Select one of the following options:\n");
    
    scanf("%c", &choice);
    
    switch(choice){
    
        case 'F' : case 'f':
            printf("Please wait while the array is being filled...\n");
            printf("Process is complete.\n");
            break;
        
        case 'P' : case 'p':
            for(i = 0; i < SIZE; i++){
                printf("%i ", rand() %(999 - 1) +1);}
        break;
        
        case 'Q' : case 'q':
            printf("Please enter element you would like to query:\n");
        
        case 'Z' : case 'z':
            printf("Goodbye\n");
            return(0);
        default:
            printf("Please select from the menu\n");}
    }
    while(choice != Z || z);
    return (0);


}

If you want to fill the array in 'F' you need a loop, very similar to what you now have in 'P'. The difference is that you will store the random numbers being generated to an element of the array.

In 'P' you need to print each element of your array, not generate random numbers. Do you know how to access individual members of your array?

Jim

Seriously guys, Do I have to bold the text FOR NOVICE USERS.

Why should you do that, novice users should never Never NEVER use goto, period. They need to learn the proper way to program not the easy way.

Jim

Originally Posted by jimblumberg

If you want to fill the array in 'F' you need a loop, very similar to what you now have in 'P'. The difference is that you will store the random numbers being generated to an element of the array.

In 'P' you need to print each element of your array, not generate random numbers. Do you know how to access individual members of your array?

Jim

No I dont know how to access elements of an array. Let alone assign random numbers to each element within the array.

Originally Posted by jimblumberg

Why should you do that, novice users should never Never NEVER use goto, period. They need to learn the proper way to program not the easy way.

Jim

Well then, thankfully this is not about learning him the most common, known and good way. As it is clear, that way has already been spoken. I was one, to bring another idea for him to chooce from. An idea that has its benefits. Thanks.

No I dont know how to access elements of an array. Let alone assign random numbers to each element within the array.

Then you may find this link useful.

I was one, to bring another idea for him to chooce from.

A very bad idea at that. Pushing the idea of using goto is like throwing someone into a well to get some water instead of teaching them to use the bucket, or pump.

Jim