Automatically run code again in C

Question

I want the user to be able to immediately re-enter another value if the value originally entered is less than 0 or more than 23. Currently, my code outputs "please re-enter a value less than 24" and stops. It then has to be run again before the user can re-input another value.

{
    printf ("What is the height of the half-pyramids?\n");
        int height = get_int();
        if (height>23)
        {
            printf("please re-enter a value less than 24\n");
        }
        else if (height<0)
        {
            printf("please re-enter a value more than 0\n");
        }
        else
        {
            printf("%i", height);
    }

}

Use a `while(1)` loop. Break out of it when the user's input is valid. — Barmar, Sep 21 '17 at 17:32
sorry, do you mind giving a more detailed example? i'm very new to this — noviceengineer13, Sep 21 '17 at 17:34
@noviceengineer13 What about reading a book covering the basics of the c language instead of asking here? — user0042, Sep 21 '17 at 17:37

score 2 · Answer 1 · answered Sep 21 '17 at 17:34

Use a loop.

while(1) {
    printf ("What is the height of the half-pyramids?\n");
    int height = get_int();
    if (height>23)
    {
        printf("please re-enter a value less than 24\n");
    }
    else if (height<0)
    {
        printf("please re-enter a value more than 0\n");
    }
    else
    {
        printf("%d\n", height);
        break; // stop stop looping
}

BTW, it's more idiomatic to use %d to print integers, not %i. See What is the difference between conversion specifiers %i and %d in formatted IO functions (*printf / *scanf)

score 2 · Answer 2 · answered Sep 21 '17 at 17:34

You could use a do-while loop:

do {
    printf ("What is the height of the half-pyramids?\n");
    int height = get_int();
    if (height > 23) {
        printf("please re-enter a value less than 24\n");
    } else if (height <= 0) {
        printf("please re-enter a value more than 0\n");
    }
    else {
        printf("%i", height);
    }
} while (height <= 0 || height > 23);

Automatically run code again in C

2 Answers2