Sorry for the NOOB question..

[Zach Heath]

I'm just starting C and haven't done programming for a few
years...could you guys please take a look at this? Thanks for your
time!

I have an input file that looks like:

1.5 2.5 Bob, Joe
4.5 5.5 Bob, Jolene

The first time through the do while loop it works fine but the second
time it looks like this:
Bob, Joe 38.50 12.75 490.88
Jolene 0.00 0.00 0.00
, Janet 0.00 0.00 0.00
- It cuts off last name and all of the floats show up zeros...

command line: ./a.out < inputFile.c

int main()
{
float inHrs, inRt, myTot;
char inName[16];

do {
/* while ( fgets(inName, sizeof(inName), stdin) ) {
*/ scanf ( "%f%f", &inHrs, &inRt );
myTot = inHrs * inRt;

fgets( inName, sizeof( inName ), stdin);

char * p = strchr( inName,'\n' );
if ( p != NULL ){
*p = '\0';
};

printf ( "%s\t%4.2f %4.2f %4.2f \n", inName, inHrs,
inRt, myTot );
inHrs = 0;
inRt = 0;
} while ( fgets(inName, sizeof(inName), stdin) != NULL );
/*
};
*/
return 0;
}

[Charlie Gordon]

"Keith Thompson" <ks***@mib.or ga écrit dans le message de news:
ln************@ nuthaus.mib.org...

"Charlie Gordon" <ne**@chqrlie.o rgwrites:

>"Lafatus" <he*****@gmail. coma écrit dans le message de news:
11************* *********@50g20 00...legro ups.com...

>>>I wasn't really planning on using a do/while, I wanted to use a while
loop but reached that point where I was trying everything and was
getting frustrated that I couldn't complete such a simple program.

As a rule of thumb, do/while loops are more difficult master than regular
while or far loops.

Let me guess, "far loops" are a DOS-specific extension that allows the
code for the loop body to span more than one memory segment, right?

You too remember the Pharlap days ;-)

(In case anyone is confused, that was a joke; "far loops" is a typo
for "for loops".)

yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master than regular
while or for loops.

--
Chqrlie.

[Keith Thompson]

CBFalconer <cb********@yah oo.comwrites:
[...]

You should also realize that google is not the messageing system,
it is only a rather poor form of message reader, with which you can
interface via http. It is so bad, and attracts so many Usenet
ignorant newbies, that many readers simply ban all messages
originating on google. So you would be well advised to get a
proper Usenet message reader, such as Thunderbird.

That's a trifle overstated. It is possible to post properly to Usenet
using Google Groups. (But I think the folks who manage to do so are
mostly people who have used real newsreaders in the past.)

The previous poster erred in posting a followup with no context, but
that's not Google's fault; the misfeature that encouraged this was
corrected some time ago, and it's a mistake that can easily be made
with a real newsreader as well.

See <http://cfaj.freeshell. org/google/>.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[CBFalconer]

Keith Thompson wrote:

CBFalconer <cb********@yah oo.comwrites:
[...]

>You should also realize that google is not the messageing system,
it is only a rather poor form of message reader, with which you
can interface via http. It is so bad, and attracts so many Usenet
ignorant newbies, that many readers simply ban all messages
originating on google. So you would be well advised to get a
proper Usenet message reader, such as Thunderbird.

That's a trifle overstated. It is possible to post properly to
Usenet using Google Groups. (But I think the folks who manage to
do so are mostly people who have used real newsreaders in the past.)

But finding out how to post properly through Google will not get
anyone past the traps set to eliminate all google posters. A
proper newsreader will.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

--
Posted via a free Usenet account from http://www.teranews.com

[CBFalconer]

Charlie Gordon wrote:

>

.... snip much banditry ...

>
yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

--
Posted via a free Usenet account from http://www.teranews.com

[Charlie Gordon]

"CBFalconer " <cb********@yah oo.coma écrit dans le message de news:
46************* **@yahoo.com...

Charlie Gordon wrote:

>>

... snip much banditry ...

>>
yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

My own experience proofreading millions on lines of C code tells me that.
It is not a matter of complexity... it is just more error prone.
do/while loops written by average programmers tend to have more bugs than
regular for or while loops.
do/while loops produced by newbies tend to be always wrong.
A great classic is this:

int c;
/* skip to end of line */
do {
c = getc(fp);
} while (c != '\n');

Of course regular while loops can be bogus too:

while (!feof(fp)) {
fgets(buf, sizeof buf, fp);
/* do something or naught */
}

Please do the test, take any project at random to which you can access the
source code and examine the do/while loops, you will find bugs!

--
Chqrlie

[Ben Bacarisse]

"Charlie Gordon" <ne**@chqrlie.o rgwrites:

"CBFalconer " <cb********@yah oo.coma écrit dans le message de news:
46************* **@yahoo.com...

>Charlie Gordon wrote:

>>>

... snip much banditry ...

>>>
yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

My own experience proofreading millions on lines of C code tells me
that.

....and my experience teaching programming leads to the same
conclusion. There seems to be something seductive about do ... while.
So much so that I just dropped the form from lecture notes as soon as
I saw the problem.

It may be that it reads naturally. It might also be that one of the
rare cases when it is correct:

do {
print prompt;
get reply;
} while (reply not suitable);

crops up in beginners programs more often than production code and the
idea sticks.

<snip>

A great classic is this:

int c;
/* skip to end of line */
do {
c = getc(fp);
} while (c != '\n');

Yes, but that is not wrong because of the do .. while. You probably
intended to leave out the declaration of c (or at least to add
.... suggesting more intervening code) so that this code comes after
some other input that might already have set c to '\n' (at least that
is the form of this bug I've seen repeatedly in student code).

--
Ben.

[Charlie Gordon]

"Ben Bacarisse" <be********@bsb .me.uka écrit dans le message de news:
87************@ bsb.me.uk...

"Charlie Gordon" <ne**@chqrlie.o rgwrites:

>"CBFalconer " <cb********@yah oo.coma écrit dans le message de news:
46************* **@yahoo.com...

>>Charlie Gordon wrote:

... snip much banditry ...

yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

My own experience proofreading millions on lines of C code tells me
that.

...and my experience teaching programming leads to the same
conclusion. There seems to be something seductive about do ... while.
So much so that I just dropped the form from lecture notes as soon as
I saw the problem.

I'm glad to see I'm not alone in the desert.

It may be that it reads naturally. It might also be that one of the
rare cases when it is correct:

do {
print prompt;
get reply;
} while (reply not suitable);

crops up in beginners programs more often than production code and the
idea sticks.

<snip>

>A great classic is this:

int c;
/* skip to end of line */
do {
c = getc(fp);
} while (c != '\n');

Yes, but that is not wrong because of the do .. while. You probably
intended to leave out the declaration of c (or at least to add
... suggesting more intervening code) so that this code comes after
some other input that might already have set c to '\n' (at least that
is the form of this bug I've seen repeatedly in student code).

That's a good point, but there is worse: this loop will run forever if the
stream ends without a new-line.
The classic idiom is safer:

while ((c = getc(fp)) != EOF && c != '\n')
continue;

or if EOF is a condition worth reporting:

while ((c = getc(fp)) != '\n') {
if (c == EOF) {
report_error("u nexpected end of file);
break;
}
}

For some reason, people tend to overlook special cases when they program
even the simplest tasks with do/while loops.

--
Chqrlie.

[Keith Thompson]

Ben Bacarisse <be********@bsb .me.ukwrites:

"Charlie Gordon" <ne**@chqrlie.o rgwrites:

>"CBFalconer " <cb********@yah oo.coma écrit dans le message de news:
46************* **@yahoo.com...

>>Charlie Gordon wrote:

... snip much banditry ...

yes, many typos in this post (un loupé)

As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

My own experience proofreading millions on lines of C code tells me
that.

...and my experience teaching programming leads to the same
conclusion. There seems to be something seductive about do ... while.
So much so that I just dropped the form from lecture notes as soon as
I saw the problem.

[...]

I learned Pascal before I learned C. In Pascal, I used
REPEAT
...
UNTIL <condition>;
(similar to C's do-while) much more than I used
WHILE <conditionDO
BEGIN
...
END;

In C, I think the last time I used a do-while loop was in my IOCCC
entry.

Pascal's I/O model, unlike C's, encourages test-at-the-bottom loops.
(Well, C's I/O model seems to encourage such loops too, but not in
correct code.)

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[user923005]

On Sep 15, 1:10 pm, Keith Thompson <[e-mail] rote:

Ben Bacarisse <ben.use...@bsb .me.ukwrites:

"Charlie Gordon" <n...@chqrlie.o rgwrites:

"CBFalconer " <cbfalco...@yah oo.coma écrit dans le message de news:
46EB2D39.3E79C. [e-mail]...
Charlie Gordon wrote:

>... snip much banditry ...

>>yes, many typos in this post (un loupé)

>>As a rule of thumb, do/while loops are more difficult to master
than regular while or for loops.

>Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

My own experience proofreading millions on lines of C code tells me
that.

...and my experience teaching programming leads to the same
conclusion. There seems to be something seductive about do ... while.
So much so that I just dropped the form from lecture notes as soon as
I saw the problem.

[...]

I learned Pascal before I learned C. In Pascal, I used
REPEAT
...
UNTIL <condition>;
(similar to C's do-while) much more than I used
WHILE <conditionDO
BEGIN
...
END;

In C, I think the last time I used a do-while loop was in my IOCCC
entry.

Pascal's I/O model, unlike C's, encourages test-at-the-bottom loops.
(Well, C's I/O model seems to encourage such loops too, but not in
correct code.)

To me, the choice is clear:

1. If you always want to perform the code _at least_ once, then use
do {} while(cond);
2. If you may not want to perform the code even one time (because
cond is false), then use while (cond) {} ;

I don't see any reason why one is easier or harder to understand than
the other. To me the complexity is identical.

[Charlie Gordon]

On Sep 15, 1:10 pm, Keith Thompson <[e-mail] rote:

>Ben Bacarisse <ben.use...@bsb .me.ukwrites:

>>"Charlie Gordon" <n...@chqrlie.o rgwrites:
"CBFalcone r" <cbfalco...@yah oo.coma écrit dans le message de news:
46EB2D39.3E7 [e-mail] ...
Charlie Gordon wrote:
>>
>As a rule of thumb, do/while loops are more difficult to master
>than regular while or for loops.

>>>>Why should you think that? "do { something() } while(foo);" is no
more complex than "while (foo) {something())". The only difference
is that the foo test is applied after execution in the do/while
loop, and before execution in the while loop.

>>>My own experience proofreading millions on lines of C code tells me
that.

>>...and my experience teaching programming leads to the same
conclusion. There seems to be something seductive about do ... while.
So much so that I just dropped the form from lecture notes as soon as
I saw the problem.

[...]

I learned Pascal before I learned C. In Pascal, I used
REPEAT
...
UNTIL <condition>;
(similar to C's do-while) much more than I used
WHILE <conditionDO
BEGIN
...
END;

In C, I think the last time I used a do-while loop was in my IOCCC
entry.

Pascal's I/O model, unlike C's, encourages test-at-the-bottom loops.
(Well, C's I/O model seems to encourage such loops too, but not in
correct code.)

To me, the choice is clear:

1. If you always want to perform the code _at least_ once, then use
do {} while(cond);
2. If you may not want to perform the code even one time (because
cond is false), then use while (cond) {} ;

I don't see any reason why one is easier or harder to understand than
the other. To me the complexity is identical.

The debate is not so simple.
The example I gave is typical of erroneous uses do/while:

people write

do {
operation;
maybe_more_oper ations;
} while (cond);

where they should write

while (operation, cond && other_cond) {
maybe_more_oper ations;
}

or

for (;;) {
operation;
if (!cond)
break;
if (!other_cond)
break;
}

definitely the do/while *seems* simpler and more straightforward , but
it tends to be bogus with conditions ignored or tested at the wrong
place.

--
Chqrlie.