CODEWITHSUNDEEP
cfunctionloopsbreak
bobblehead808
bobblehead808

Reputation: 63

How do I return to the Beginning of my Program without a Goto Statement

#include <stdio.h>
#include <math.h>

long factcalc(int num1);

int main(void) 
{
    int num1;
    long factorial;
    int d;
    int out;

    printf("Please enter a number that is greater than 0");
    scanf_s("%d", &num1);

    if (num1 < 0) {
        printf("Error, number has to be greater than 0");
    } else if (num1 == 0) {
        printf("\nThe answer is 1");
    } else {
        factorial = factcalc(num1);
        printf("\nThe factorial of your number is\t %ld", factorial);
    }

    return 0;
}

long factcalc(int num1) 
{
    int factorial = 1;
    int c;

    for (c = 1; c <= num1; c++)
    factorial = factorial * c;

    return factorial;
}

I was wondering, how do I make it so that the program keeps asking the user for input until the user inputs '-1'? So that even after it has calculated the factorial of one number it keeps asking for more numbers until -1 is put in by the user, same goes for when it displays the error message and such. Thanks in advance.

Upvotes: 0

Views: 4768

Answers (3)

cm161
cm161

Reputation: 510

Yes, as suggested by @ameyCU, using loop is solution. For example, 

while (1)
{
    printf("Please enter a number that is greater than 0");
    scanf_s("%d", &num1);

    if (-1 == num1)
    {
        break;
    }

    // Find factorial of input number
    ...
    ...

    // Loop back to get next input from user
}

Upvotes: 0

Jameson
Jameson

Reputation: 6679

There are a select few scenarios where using goto is "okay," but this is surely not one.

First, put the relevant bits of your program into functions.

Then, monitor and use the user input like so:

int number = -1;

while (scanf("%d", &number)) {
    if (-1 == number) {
        break;
    }

    call_foo_function(number);
}

Upvotes: 1

MikeCAT
MikeCAT

Reputation: 75062

It can be easily achieved by introducing an infinite loop.

#include <stdio.h>
#include <math.h>

#ifndef _MSC_VER
#define scanf_s scanf
#endif

long factcalc(int num1);

int main(void)
{
    int num1;
    long factorial;
    int d;
    int out;

    for (;;) {
        printf("Please enter a number that is greater than 0");
        scanf_s("%d", &num1);
        if (num1 == -1) {

            break;
        }

        else if (num1 < 0) {

            printf("Error, number has to be greater than 0");
        }

        else if (num1 == 0) {

            printf("\nThe answer is 1");
        }

        else {

            factorial = factcalc(num1);
            printf("\nThe factorial of your number is\t %ld", factorial);
        }
    }

    return 0;
}

long factcalc(int num1) {

    int factorial = 1;
    int c;

    for (c = 1; c <= num1; c++)
        factorial = factorial * c;

    return factorial;
}

Upvotes: 5

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