getc(fp) causing trouble

Question

Here is my code.

#include<stdlib.h>
#include<stdio.h>
int main(int argc,char** argv)
{
    char a;
    a=9;
    FILE * fp;
    fp=fopen(argv[1],"r");
    while(a!= EOF)
    {
        a=fgetc(fp);
        printf("\n%d",a);
    }
}

The output to this is alright but at the end I am getting a weird character with -1 (since I am printing integer value.

How to stop it at EOF only? Also what is this character?

don't forget to check fopen() return value – Yann Droneaud Feb 21 '12 at 13:14 — Yann Droneaud, Feb 21 '12 at 13:14
and do not forget the fclose() – Peter Miehle Feb 21 '12 at 15:27 — Peter Miehle, Feb 21 '12 at 15:27

hmjd · Answer 1 · 2012-02-21T16:11:47.450

2

You are printing the EOF character (the -1) as you do not check if EOF was encountered immediately after fgetc(). Change the structure of the loop to:

int a; /* not char, as pointed out by R... */

for (;;)
{
    a = fgetc(fp);
    if (EOF == a) break;
    printf("\n%d", a):
}

edited Feb 21 '12 at 16:11

answered Feb 21 '12 at 13:05

hmjd

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This does not fix the problem that `a` has the wrong type (`char` instead of `int`)... – R.. GitHub STOP HELPING ICE Feb 21 '12 at 15:56
Yes, but just in hopes of getting OP to notice the correct answer below before blindly accepting something. Removed it now. – R.. GitHub STOP HELPING ICE Feb 21 '12 at 16:15

Some programmer dude · Accepted Answer · 2012-02-21T19:48:44.113

2

Besides the methods in the other answers, you can also do like this:

while ((a = fgetc(fp)) != EOF)
{
    printf("%d\n", a);
}

Now you have a few alternative solutions. :)

Edit: As R.. so kindly reminds us, you also have to change the type of a to int.

edited Feb 21 '12 at 19:48

answered Feb 21 '12 at 13:25

Some programmer dude

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this is the most-seen solution in C – Peter Miehle Feb 21 '12 at 15:26

score 1 · Answer 3 · answered Feb 21 '12 at 14:00

1

You need to make a have type int, as that type is the return type of fgetc(), and is needed to represent EOF correctly.

answered Feb 21 '12 at 14:00

unwind

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score 0 · Answer 4 · answered Feb 21 '12 at 13:05

0

Why don't you stop the while with this condition:

do {...}while(a != EOF)

I suppose that a got EOF value AFTER read it. So, you do the cycle an extra time

answered Feb 21 '12 at 13:05

DonCallisto

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This will run through the loop at least once, and still print `-1` if `fgetc` returns `EOF` immediately. – Some programmer dude Feb 21 '12 at 13:29

getc(fp) causing trouble

4 Answers4

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