Thread: Global space

I was just wondering if i can expect anything bad from the following code, or whether it is just bad programming practice

Code:

#include <stdio.h>
#include <stdlib.h>
const int RUNNING = 1;
int correct = 0, wrong = 0;

most notably the last line.


also how do i declare these - the last line - in main and have all my functions access them? do i need to use extern or is there another way? and why does it give me an error msg when i do try to have a function call it from main()?

thanks.

Just pass them as parameters to your functions. If the function will be changing the value, you'll need to pass a pointer to the variable.

no, no they are not constants. I'm using them to see how many answers a user has right and wrong. However I want to declare them once and then call them in ANY function called from main. is ther a way for this, aside maybe from extern.

Thanks.

1) Use globals, as you've done:

Code:

#include stuff here

int myglobal;

void fun( void )
{
    myglobal = 10;
}

void showglobal( void )
{
    printf("myglobal is %d", myglobal );
}

int main( void )
{
    myglobal = 4;
    showglobal();

    fun();
    showglobal();

    myglobal--;
    showglobal();

    return 0;
}

That's a poor way to do it. But some times, used sparingly, it works out ok.

2) Pass the variable via function calls:

Code:

#include stuff here

void somefunction( int x )
{
    printf("x is %d\n", x );
}

void someotherfunction( int *x )
{
    printf("x is %d, ", *x );
    *x = 234;
    printf("but now it's %d!\n", *x );

}

int yetanotherfunction( void )
{
    printf("Changing your variable via return value...\n");

    return 1034;
}

int main( void )
{
    int myvariable = 0;

    somefunction( myvaraible ); /* available, but won't be modified */
    printf("myvariable is %d\n", myvariable );

    someotherfunction( &myvariable ); /* available, can be modified */
    printf("myvariable is %d\n", myvariable );

    myvariable = yetanotherfunction( ); /* modified by the return value */
    printf("myvariable is %d\n", myvariable );
    return 0;
}

Enjoy.

Quzah.

Thanks guys, I used it as a global variable first, but i've heard it said that globals should be used sparingly - if at all. However I find it annoying to pass them as parameters to the functions I need them to work with, i have like 6 or seven and yeah i have to write it only once in those functions but it is still redundant. know what i mean.