CODEWITHSUNDEEP
cloopsfor-loop
Adam J
Adam J

Reputation: 27

Why isn't this 'for loop' exiting? C

I'm quite a beginner with C, and I'm just wondering why this 'for loop' isn't exiting:

int main()
{
    FILE *openfile;
    int notenumber;

    openfile = fopen("test.txt", "w");

        if (openfile == NULL)
        {
            printf("Error opening file\n");
        }
        else
        {
            for (notenumber=1; notenumber<=16; notenumber++)
            {
                notenumber = aserveGetNote();
                fprintf(openfile, "Notenumber = %d\n", notenumber);         
            }

        }

        fclose(openfile);


    return 0;
}

I don't understand why the loop will not exit. Even if I remove the if else loop and just have the for loop, I still have the same problem?

Upvotes: 0

Views: 106

Answers (3)

ChristianMurschall
ChristianMurschall

Reputation: 1711

The question is already answered. One more hint: You do check after fopen for NULL. but what would happen if you do get a NULL and call fclose? On my machine I get a segmentation fault error.

Upvotes: 0

francis
francis

Reputation: 9817

notenumber = aserveGetNote(); : if aserveGetNote() always returns something below 16, the for loop can't be completed.

Try 

for (notenumber=1; notenumber<=16; notenumber++)
        {
            int note = aserveGetNote();
            fprintf(openfile, "Note = %d Notenumber %d\n", note,notenumber);         
        }

And follow the advice of @iharob : put fclose() in the else part of the test, to avoid calling fclose() on NULL.

Welcome to Stackoverflow !

Upvotes: 1

ForceBru
ForceBru

Reputation: 44906

aserveGetNote() changes the value of notenumber to something below 16, so the loop never exits as notenumber<=16; is always true.

You can solve the problem by doing like this:

int test=aserveGetNote();
fprintf(openfile, "Notenumber = %d\n", test);
// or fprintf(openfile, "Notenumber = %d\n", notenumber); as I don't know which value do you want to store

Upvotes: 2

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