fscanf

[Bill Cunningham]

I'm doing something wrong and all I know to do is turn to clc. I have a
text file containing 2 doubles separated by a tab.

..26 0

Is the text. I want to read the two double and printf them out. Here's my
file.

#include <stdio.h>

int main() {
FILE *fp;
double x,y;
fp=fopen("zo"," r"); /*error checking out for brevity */
fscanf(fp,"%.2f \t%.2f",&string );
fclose(fp);
printf("%.2f%.2 f",x,y);
}

All I get is garbage that is contained in x and y. For whatever simple
reason that is beyond me evidently I can't read and printf out to stdin from
this text file. I don't think fread is really necessary.

Bill

[vippstar]

On Aug 18, 2:39 am, "Bill Cunningham" <nos...@nspam.c omwrote:

I'm doing something wrong and all I know to do is turn to clc. I have a
text file containing 2 doubles separated by a tab.

.26 0

Is the text. I want to read the two double and printf them out. Here's my
file.

#include <stdio.h>

int main() {
FILE *fp;
double x,y;
fp=fopen("zo"," r"); /*error checking out for brevity */
fscanf(fp,"%.2f \t%.2f",&string );
fclose(fp);
printf("%.2f%.2 f",x,y);

}

All I get is garbage that is contained in x and y. For whatever simple
reason that is beyond me evidently I can't read and printf out to stdin from
this text file. I don't think fread is really necessary.

You're a liar, Bill. That code does not compile, so it's impossible
for you to get anything out of executing this program.

[Anand Hariharan]

On Sun, 17 Aug 2008 23:39:25 +0000, "Bill Cunningham" <no****@nspam.c om>
wrote:

I'm doing something wrong and all I know to do is turn to clc. I have a
text file containing 2 doubles separated by a tab.

.26 0

Is the text. I want to read the two double and printf them out. Here's
my file.

<snipped code>

Please post the *actual* code that you used to compile and generate the
executable that caused garbage to be printed. The code you posted will
not compile.

- Anand

[Bill Cunningham]

"Anand Hariharan" <zn************ ********@tznvy. pbzwrote in message
news:g8******** **@aioe.org...

Please post the *actual* code that you used to compile and generate the
executable that caused garbage to be printed. The code you posted will
not compile.

Ok I did write this on the fly. I will look again at the actual code.

Bill

[Bill Cunningham]

"Bill Cunningham" <no****@nspam.c omwrote in message
news:yx3qk.131$ w51.17@trnddc01 ...

Ok I did write this on the fly. I will look again at the actual code.

#include <stdio.h>

int main() {
FILE *fp;
double x,y;
fp=fopen("zo"," a");
fscanf(fp,"%.2f \t%.2f",&x,&y);
fclose(fp);
printf("%.2f\t% .2f",x,y);
}

Now this compiled for me with the results 0.00 and 4.87. Not the text
from the file called "zo". The only real difference here is the text mode is
append and not read.

Bill

[Ian Collins]

Bill Cunningham wrote:

"Bill Cunningham" <no****@nspam.c omwrote in message
news:yx3qk.131$ w51.17@trnddc01 ...

>Ok I did write this on the fly. I will look again at the actual code.

#include <stdio.h>

int main() {
FILE *fp;
double x,y;
fp=fopen("zo"," a");
fscanf(fp,"%.2f \t%.2f",&x,&y);
fclose(fp);
printf("%.2f\t% .2f",x,y);
}

Now this compiled for me with the results 0.00 and 4.87. Not the text
from the file called "zo". The only real difference here is the text mode is
append and not read.

So what does your documentation well you about append mode?

--
Ian Collins.

[Bill Cunningham]

"Ian Collins" <ia******@hotma il.comwrote in message
news:6g******** ****@mid.indivi dual.net...

So what does your documentation well you about append mode?

It just says append is a possible mode with a+ also which is append-read
mode. Plus this book tells me that garbage about using t if I want for text
mode. I know that's not portable stdc.
http://www.cppreference.com/stdio/fopen.html

Is my main online reference. I've been thinking my trouble is in fscanf. It
might be in fopen's mode.

Bill

[Ian Collins]

Bill Cunningham wrote:

"Ian Collins" <ia******@hotma il.comwrote in message
news:6g******** ****@mid.indivi dual.net...

>So what does your documentation well you about append mode?

It just says append is a possible mode with a+ also which is append-read
mode. Plus this book tells me that garbage about using t if I want for text
mode. I know that's not portable stdc.
http://www.cppreference.com/stdio/fopen.html

Is my main online reference.

Well it's a piss-poor one if that page is anything to go by. I suggest
you look up the definition of "append"

--
Ian Collins.

[Paul]

Bill Cunningham wrote:

"Ian Collins" <ia******@hotma il.comwrote in message
news:6g******** ****@mid.indivi dual.net...

>So what does your documentation well you about append mode?

It just says append is a possible mode with a+ also which is append-read
mode. Plus this book tells me that garbage about using t if I want for text
mode. I know that's not portable stdc.
http://www.cppreference.com/stdio/fopen.html

Is my main online reference. I've been thinking my trouble is in fscanf. It
might be in fopen's mode.

Bill

http://linux.die.net/man/3/fopen

"The argument mode points to a string beginning with one of the following
sequences (Additional characters may follow these sequences.):

a Open for appending (writing at end of file). The file is created if
it does not exist. The stream is positioned at the end of the file. <---- yikes

"

http://linux.die.net/man/3/fscanf

"Return Value

These functions return the number of input items successfully matched and assigned,
which can be fewer than provided for, or even zero in the event of an early matching
failure.

The value EOF is returned if the end of input is reached before either the first
successful conversion or a matching failure occurs. EOF is also returned if a read
error occurs, in which case the error indicator for the stream (see ferror(3)) is
set, and errno is set indicate the error."

Defensive programming, means checking the values returned by things like fscanf.
Wouldn't you be curious, whether fscanf converted zero, one, or two items ? If the
answer is not two, then X or Y could contain bogus information. And if an end of
file was encountered, you'd probably want to know about that also. There are many
possible outcomes, when handling file I/O.

Paul

[Bill Cunningham]

"Paul" <no****@needed. comwrote in message news:g8******** **@aioe.org...

[snip]

Defensive programming, means checking the values returned by things like
fscanf.
Wouldn't you be curious, whether fscanf converted zero, one, or two items
? If the
answer is not two, then X or Y could contain bogus information. And if an
end of
file was encountered, you'd probably want to know about that also. There
are many
possible outcomes, when handling file I/O.

Paul

Like this you mean?

fscanf(fp,"%.2f \t%.2f",&x,&y);
if (fp==EOF)
puts("fscanf error");
Bill