Thread: break & switch statement

I have just started learning C language. I'm using a book by Greg Perry & Dean Miller. Explaining the "break & switch" statements they have as an example the code that follows. At the end of the program they use the following statement: - while ((choice < 1) || (choice> 5)); - Compiled, the program works. In my limited knowledge of C language, it should not work for the variable "choice" is actually larger than 1 and smaller than 5. The expresion ought to read - while ((choice > 1) || (choice < 5)); - instead. Your input would be greatly appretiated. Thanks



Code:

/* The code listing from chapter 17 of The Absolute Beginner's Guide to C
Teaching new programmers to create kick-butt code since 1941! */
/* A Dean Miller joint */
/* Filename Chapter17ex1.c */
/* This program presents a menu of choices, gets the user's choice,
   and then uses the switch statement to execute a line or two of
   code based on that choice. What the user wants to do is never
   truly implemented, it is a series of stubs to teach the value
   of the switch statement */

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

int main ()

    {
    int choice;
    printf("What do you want to do?\n");
    printf("1.- Add a new contact\n");
    printf("2.- Edit existing contact\n");
    printf("3.- Call existing contact\n");
    printf("4.- Text existing contact\n");
    printf("5.- Exit\n");
    do

    {
        printf("Enter your choice: ");
        scanf(" %d", &choice);
        switch (choice)

            {
            case (1): printf("\nTo add you will need ");
                 printf("the contact's first name, ");
                 printf("last name and number.\n");
                 break;
            case (2): printf("\nGet ready to enter the ");
                 printf("name of the contact ");
                 printf("you wish to edit.\n");
                 break;
            case (3): printf("\nWhich contact do ");
                 printf("you wish to call\n");
                 break;
            case (4): printf("\nWhich contact do ");
                 printf("you wish to text\n");
                 break;
            case (5): exit(1); // exits the program early
                 break;
            default: printf("\n%d is not a valid choice.\n", choice);
                 printf("Try again\n");
                 break;
            }
        }

        while ((choice < 1) || (choice > 5));

    return 0;

    }




• Ignore
• Add to Dictionary

• Ignore
• Add to Dictionary

Originally Posted by tabstop

That depends on what you think the purpose of the loop is, I suppose. Based on what's printed, I would say that we want to keep looping if the user has entered an invalid number (too big or too small), so that is how the loop is written. If the value of choice is 1, 2, 3, or 4, we execute the single case and then stop.

I´m not clear, but thank you tabstop. It was my understanding that the loop´s purpose was for the program to cycle 1 to 5 in terms of choices for the user. Default within switch was to take care of invalid entry. Again thanks

default: printf("\n%d is not a valid choice.\n", choice);
printf("Try again\n");
break;

• Ignore
• Add to Dictionary

• Ignore
• Add to Dictionary

It is saying - "If the user has entered below 1 or above 5, do the loop again"