Code is outputting a random integer, changes every time I run it

[SofaWolf]

Heya. I have no idea why it's doing this, I've been tweaking and changing the code for the past hour and it still won't work.

/* A program to change headings in degrees into bearings */


#include <stdio.h>


int input(); //gets degrees from user
char directionmake(); //calculates direction
int calc(); //calculates degrees to turn after direction


int main()
{
    int degrees;
    degrees = input();
    char direction;
    direction = directionmake(degrees);
    degrees = calc(degrees);
    printf("\n\n%c, \n\n", direction);
    printf("%d", degrees);
    return 0;
} // program execution


int input()
{
    int degrees;
    printf("Please state the heading in degrees: ");
    scanf("%d", &degrees);
    return degrees;
}


char directionmake()
{
    char direction;
    int degrees;
    if (degrees < 0)
        printf("Bad input");
    else if (degrees < 90)
        direction = 'N';
    else if (degrees < 270)
        direction = 'S';
    else if (degrees <= 360)
        direction = 'N';
    return direction;
}


int calc()
{
    int degrees;
    if (degrees > 90 && degrees < 180)
        degrees = degrees - 90;
    else if (degrees > 180 && degrees < 270)
        degrees = degrees - 180;
    else if (degrees > 270 && degrees <180)
        degrees = degrees - 270;


    return degrees;
}

I feel like there's something blatantly wrong, but I can't see it...

Thanks.

[stahta01]

Learn to pass parameter to functions!

Try reading this link info http://www.cprogramming.com/tutorial/c/lesson4.html

int calc()
{
    int degrees; /* local variable that could have random value */
    if (degrees > 90 && degrees < 180)
        degrees = degrees - 90;
    else if (degrees > 180 && degrees < 270)
        degrees = degrees - 180;
    else if (degrees > 270 && degrees <180)
        degrees = degrees - 270;
 
 
    return degrees;
}

[SofaWolf]

Like this?

#include <stdio.h>


int input(); //gets degrees from user
char directionmake(); //calculates direction
int calc(int degrees); //calculates degrees to turn after direction


int main()
{
    int degrees;
    degrees = input();
    char direction;
    direction = directionmake(degrees);
    degrees = calc(degrees);
    printf("\n\n%c, \n\n", direction);
    printf("%d", degrees);
    return 0;
} // program execution


int input()
{
    int degrees;
    printf("Please state the heading in degrees: ");
    scanf("%d", &degrees);
    return degrees;
}


char directionmake()
{
    char direction;
    int degrees;
    if (degrees < 0)
        printf("Bad input");
    else if (degrees < 90)
        direction = 'N';
    else if (degrees < 270)
        direction = 'S';
    else if (degrees <= 360)
        direction = 'N';
    return direction;
}


int calc(int degrees)
{
    if (degrees > 90 && degrees < 180)
        degrees = degrees - 90;
    else if (degrees > 180 && degrees < 270)
        degrees = degrees - 180;
    else if (degrees > 270 && degrees < 360)
        degrees = degrees - 270;


    return degrees;
}

Edit: Now it passes degrees to it, but it doesn't subtract the numbers.

Edit: Somehow I fixed it, I have no idea how though.

This is the working code:

/* Program 4 - A program to change headings in degrees into bearings */


#include <stdio.h>


int input(); //gets degrees from user
char directionmake(); //calculates direction
int calc(int degrees); //calculates degrees to turn after direction


int main()
{
    int degrees;
    degrees = input();
    char direction;
    direction = directionmake(degrees);
    degrees = calc(degrees);
    printf("\n\n%c, \n\n", direction);
    printf("%d", degrees);
    return 0;
} // program execution


int input()
{
    int degrees;
    printf("Please state the heading in degrees: ");
    scanf("%d", &degrees);
    return degrees;
}


char directionmake()
{
    char direction;
    int degrees;
    if (degrees < 0)
        printf("Bad input");
    else if (degrees < 90)
        direction = 'N';
    else if (degrees < 270)
        direction = 'S';
    else if (degrees <= 360)
        direction = 'N';
    return direction;
}


int calc(int degrees)
{
    if (degrees > 90 && degrees < 180)
        degrees = degrees - 90;
    else if (degrees > 180 && degrees < 270)
        degrees = degrees - 180;
    else if (degrees > 270 && degrees < 360)
        degrees = degrees - 270;


    return degrees;
}

[memcpy]

> Somehow I fixed it, I have no idea how though.
That's usually the result of undefined behavior, which your program certainly relies on. You should make the same change you did to "calc" to "directionmake", passing in the integer instead of making a new variable.

[SofaWolf]

> Somehow I fixed it, I have no idea how though.
That's usually the result of undefined behavior, which your program certainly relies on

I can't tell if that's an insult or not D:. Anyways, thanks, I forgot to do the same to directionmake.

[anduril462]

I'm sure it's not an insult, just a statement of fact. We're blunt, not mean.

As a side note, your calc function is simply a "remainder" or "modulo" function. You want to take degrees and turn it into a value from 0-90, so just do

return degrees % 90;

[stahta01]

return degrees % 90;

Correction that makes the value 0 to 89; I have no idea what the OP wants if the value is 90.

Tim S.

I'm sure it's not an insult, just a statement of fact. We're blunt, not mean.

As a side note, your calc function is simply a "remainder" or "modulo" function. You want to take degrees and turn it into a value from 0-90, so just do

return degrees % 90;