program for reading a file

[WANG Cong]

On Sat, 15 Mar 2008 03:38:57 -0700，broli wrote：

I use TC 2.01 on win xp and to be honest it has given me many problems.
I want to use a different and easier complier, I have looked around but
cannot find one.

TC on win sucks a lot. Don't use it. Try to use a standard-friendly
compiler, e.g. gcc, icc.

 

[santosh]

gcc -Wall (mingw version) doesn't give a warning about char c=fgetc().

lcc-win32 -A does give a warning.

Pelles C (or any other running under IDE) I wouldn't have a clue how
to set warning level.

A run through lint spots the problem immediately.

 

[santosh]

gcc -Wall (mingw version) doesn't give a warning about char c=fgetc().

lcc-win32 -A does give a warning.

Pelles C (or any other running under IDE) I wouldn't have a clue how
to set warning level.

BTW the Intel C compiler does produce a warning even at standard
diagnostic levels.

$ icc -Wall -ansi -o 0 0.c
0.c(7): remark #810: conversion from "int" to "char" may lose
significant bits
c = fgetc(stdin);
^
$

 

[Bartc]

A run through lint spots the problem immediately.

Ok there's the answer for the OP then: any inexplicable error try 'lint'
first.

 

[Nick Keighley]

Yes.

I belive it is free for *non-commercial* purposes.
But check with Jacob Navia or lcc-win32's site

 

[Barry Schwarz]

After changing to int, Im still getting an infinite loop -

#include<stdio.h>

int main(void)
{

FILE *fp;
int c;

fp = fopen("sample.dat", "r");
if(fp == NULL)
{

printf("Cannot open the file\n");
return 0;

}

while(1)
{

c = fgetc(fp);
if(c == EOF)

How are signalling EOF from your keyboard? This is system dependent.
Popular choices are ctrl-D for Unix and ctrl-Z for Windows.

{
break;
}
else
printf("%c",c);

Please learn to indent consistently and visibly. It will be a
lifesaver when you start writing larger programs. (And for stuff
posted to Usenet, use spaces, not tabs.)

}

return 0;

}

Remove del for email

 

[Richard Heathfield]

Barry Schwarz said:

How are signalling EOF from your keyboard?

He isn't. He's reading from a file.

 

[William Pursell]

fp = fopen("sample.dat", "r");
if(fp == NULL)
{

printf("Cannot open the file\n");
return 0;

3 comments: "Cannot open the file" is NOT a
useful error message, returning with success
seems wrong in this case, and it is odd to
write error messages to the output stream.
Please consider:

if( fp == NULL ) {
fprintf( stderr, "Cannot open %s: %s\n",
filename, strerror( errno ));
return EXIT_FAILURE;
}

 

[Keith Thompson]

I use TC 2.01 on win xp and to be honest it has given me many
problems. I want to use a different and easier complier, I have looked
around but cannot find one.

I see nothing wrong with the program you posted upthread (the second
version, with "int c;"). There may be good reasons to use something
other than TC 2.01 on win xp, but I seriously doubt that it's so
flawed that it would cause the program you posted to go into an
infinite loop.

Compilers do have bugs, but for the elementary kind of stuff you're
currently doing, a compiler bug shouldn't be the first thing you think
of. Make sure that the code you posted is exactly the same as the
code you're compiling, that you've recompiled it, that you're running
it properly, etc.

 

[Keith Thompson]

Here is your first mistake. Fgetc returns an int value, not a char. This
is because the out-of-band value EOF is an int. You need to store
fgetc's return value in an int, test it if it is EOF and assign to a
char only if it is an ordianary character.
Right.


This check will fail because of what I said above.

It won't *necessarily* fail, at least not visibly. I just tried the
program with "char c;", and it "worked". (It fails, by terminating
early, if I insert a 0xff character into the input file.)

It would most likely fail (with an infinite loop) on a system where
plain char is unsigned (it's signed on mine).

 

[CBFalconer]

I cannot understand why the program goes into infinite loop after
the file is printed on the screen.

#include<stdio.h>

int main(void)
{

FILE *fp;
char c;

int c;

should do it. Look up the return value from fgetc().

 

[CBFalconer]

lcc-win32.. is it freely available on jacob navias website ?

Yes, but beware - I believe it doesn't compile to the C standard.