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407
Master Cheater
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Posts: 357
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 Posted: Sun Jan 23, 2011 4:57 pm Post subject: fprintf in C help |
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| Code: | void results(FILE* in, char studentAns[], char ansKey[], int studentId[])
{
FILE* out;
out = fopen("grades.txt", "w");
if(out == NULL)
{
printf("Error opening file.\n");
}
fprintf(out, "ID\tNumber Correct\tPercent");
return;
} |
It's not printing for some reason.. I can't seem to see what the problem is..
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Slugsnack
Grandmaster Cheater Supreme
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Posts: 1857
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| Posted: Sun Jan 23, 2011 5:45 pm Post subject: |
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It works fine. I just made this short program:
| Code: | #define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main() {
FILE* out;
out = fopen("grades.txt", "w");
if(out == NULL)
{
printf("Error opening file.\n");
}
fprintf(out, "ID\tNumber Correct\tPercent");
fclose( out );
return 0;
} |
Something to note, you are missing a fclose() at the end.
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HomerSexual
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| Posted: Sun Jan 23, 2011 5:57 pm Post subject: |
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If you don't close the file handle, I don't think it will write to the file. I had that issue in java the other day.
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Slugsnack
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| Posted: Sun Jan 23, 2011 6:00 pm Post subject: |
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| Nope it works without the fclose. Also your check for the fopen is good practice but not wrapping the rest of it in an else or making it return in the case of error is not.
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407
Master Cheater
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Joined: 25 Oct 2007
Posts: 357
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| Posted: Sun Jan 23, 2011 8:34 pm Post subject: |
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| Slugsnack wrote: | | Nope it works without the fclose. Also your check for the fopen is good practice but not wrapping the rest of it in an else or making it return in the case of error is not. |
That's what I thought..
I need 2 parallel files open, because I can't re-start where I left off if I close the file, right?
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atom0s
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Posts: 8587
Location: 127.0.0.1
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| Posted: Sun Jan 23, 2011 11:08 pm Post subject: |
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| Two wrote: | | Slugsnack wrote: | | Nope it works without the fclose. Also your check for the fopen is good practice but not wrapping the rest of it in an else or making it return in the case of error is not. |
That's what I thought..
I need 2 parallel files open, because I can't re-start where I left off if I close the file, right? |
If you wrote to the end of the file just set the file pointer to the end. Look into:
fseek / fsetpos
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