Thread: Today's easy question: Can you spot the problem?

I can't, but I know it's something easy...

Code:

#include <stdio.h>
#include <stdlib.h>
int main()
{
    int first_eight_powers_of_two[7];
    int i;
    double sum_thing=2;
    int j;
        for(i=0; i<8; i++)
        {
            first_eight_powers_of_two[i]=sum_thing;
            sum_thing*=2;
        }
    i=0;
    
        do
        {
            printf("2 to the %d is:  %ld\n", i+1, first_eight_powers_of_two[i]);
            i++;
        }while(i<8);

    return EXIT_SUCCESS;
}

Your compiler would help you, if you just let it. Enable all warnings in GCC, and you'll get

Code:

gratiafide.c: In function ‘main’:
gratiafide.c:18:13: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘int’ [-Wformat]
gratiafide.c:8:9: warning: unused variable ‘j’ [-Wunused-variable]
gratiafide.c:11:38: warning: array subscript is above array bounds [-Warray-bounds]
gratiafide.c:18:19: warning: array subscript is above array bounds [-Warray-bounds]

Just start at line 5. Doesn't it strike you as odd that you say "eight", but define the array to have just seven elements?

Last night while laying in bed I realized the problem was that I had the array of size [7] without even looking at my program....

I had done 7 because I wanted to see if 7 meant 0-7, but as dojha00 points out it is actually 0-6. Thanks for the help

BTW how do I turn on all the compiler error notifications in code blocks? Also, is there a way to make code blocks compatible with a c99 compiler? Thanks.

settings -> compiler and debugger...

Check out the "compiler flags" at your disposal.

Nominal animal,

Can you please explain the warning #2 your complier got? "gratiafide.c:18:13: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘int’ [-Wformat]"

Isn't %ld correct with double variables?

Thanks.

Or if anyone else could explain it, that'd be swell.

Code:

{
    int first_eight_powers_of_two[7];
    int i;

    // ...

    printf("2 to the %d is:  %ld\n", i+1, first_eight_powers_of_two[i]);
}

"first_eight_powers_of_two[7]" is an array of integers - which doesn't appear to be what you want - but that would use %d since it's [an integer that's] not long.

"%f" is used to print doubles with "printf()".

You're probably thinking of needing "%lf" for doubles with "scanf()"

Are you sure this is correct: first_eight_powers_of_two[i]=sum_thing;
You should decide if you want double (floating point double precision) or integer. If you truly want to convert one to the other then please use floor(...) and/or (int) casting.
Then when you have figured out which type of data to store, then the printf format specifier will be obvious: %f for float or %d for int.

Yeah, I originally had it as an int, but when I was getting the array problem I changed it to double thinking that I had hit the ceiling. Thanks for the info.

I don't know if there are any compiler settings in particular you can suggest for me. That is a long list, and I tried selecting about a third of them but then couldn't compile things at all.

Don't start selecting things that you don't understand! What do you want included? "Enable all compiler warnings" is a good one to have checked.

Any way to make it c99 compatible?

Check the internet.

I have Pelles. That's c99 compatible. But I kind of like Code Blocks.

I don't use C99 - but I took my own advice and found several answers that seem to agree.

Print Page - How to change codeblocks to c99 standard?
Print Page - I can't use the C99``
C Programming question. How do I set, std=c99 on Codeblocks? - Yahoo! Answers