HOW to back for the beginning if the user press any key except 1 or 2 or 3? [closed]

by

Use do–while loop and set the condition to while(L != '1' && L != '2' && L != '3');:

do {
    L = getch();
    switch (L) {
    case '1' :
        system("cls"); 
        printf("111111111111111");
        break;
    case '2' :
        system("cls");
        printf("222222222222222");
        break;
    case '3' :
        system("cls");
        printf("33333333");
        break;
    default :
        sleep(0);
    }
} while(L != '1' && L != '2' && L != '3');

The code above will prompt for data first then evaluate it and continue these until user enters '1', '2' or '3'.

As comments bellow mention the default case with sleep(0) has no use but it can be improved e.g. as follows:

do {
    L = getch();
    switch (L) {
    case '1' :
        system("cls"); 
        printf("111111111111111");
        break;
    case '2' :
        system("cls");
        printf("222222222222222");
        break;
    case '3' :
        system("cls");
        printf("33333333");
        break;
    default :
        L = 0;
    }
} while(!L);

In this example you don’t have to double check for permitted values (assuming that you don’t want to use the case when L == 0).

As the title of your question is a bit misleading maybe I didn’t understand what do you like to achieve. If you just want to suspend going back to the beginning of your loop, you can add an extra getch() after the switch block:

while (1) {
    L = getch();

    switch (L) {
    case '1':
        system("cls"); 
        printf("111111111111111");
        break;
    case '2':
        system("cls");
        printf("222222222222222");
        break;
    case '3':
        system("cls");
        printf("33333333");
        break;
    }

    printf("Press Any Key to Continue...");
    getch();
}

If this still doesn’t answer your question I recommend you to improve it.

More Related Contents:

  1. I need help understanding this code in C [closed]
  2. Simple counters not working in C
  3. break statement doesn’t work in a loop [closed]
  4. How to iterate over this series 5 6 7 6 5 6 7 6 5 6 7 6 5… in C? [closed]
  5. Finding target sum of two numbers in array
  6. How to break out of while loop in C
  7. Disadvantages of scanf
  8. do { … } while (0) — what is it good for? [duplicate]
  9. C loop optimization help for final assignment (with compiler optimization disabled)
  10. Validate the type of input in a do-while loop C
  11. For vs. while in C programming?
  12. Effect of semicolon after ‘for’ loop
  13. Is it faster to count down than it is to count up?
  14. How to scanf only integer and repeat reading if the user enters non-numeric characters?
  15. What does `scanf(“%*[^\n]%*c”)` mean?
  16. Which is the best way to get input from user in C?
  17. No loop condition in for and while loop
  18. How to optimize these loops (with compiler optimization disabled)?
  19. Validate the type of input in a do-while loop
  20. When implementing an infinite loop, is there a difference in using while(1) vs for(;;) vs goto (in C)?
  21. Is there any way to loop through a struct with elements of different types in C?
  22. How to use int16_t or int32_t with functions like scanf [duplicate]
  23. How can I optimize these loops (with compiler optimization disabled)?
  24. How can I break out of two nested for loops in Objective-C?
  25. self referential struct definition?
  26. Getting “conflicting types for function” in C, why?
  27. Why are global variables bad, in a single threaded, non-os, embedded application
  28. Is there a meaningful distinction between freestanding and hosted implementations?
  29. How to create a new Linux kernel scheduler
  30. What is “-1L” / “1L” in C?

Leave a Comment