«

The program is supposed to read lines from the standard input, then each line is printed on the standard output preceded by its line number. The program should have no built-on limit on how long a line it can handle.

So I wrote the following program in C, but I'm not sure that it is doing what it is supposed to do. I verified the source code against the solution in the back of the book and I'm pasting here what the solution in the back of the book is.

#include<stdio.h>
#include<stdlib.h>

int main(){

int ch;
int at_beginning = 1;
int line = 0;

while( (ch==getchar())!= EOF){

if(at_beginning == 1){

at_beginning = 0;
line+=1;
printf("%d ", line);

}

putchar(ch);

if(ch == '\n')
at_beginning = 1;
}
return EXIT_SUCCESS;
}

On 1/30/2011 4:08 PM, John wrote:
> The program is supposed to read lines from the standard input, then each line is printed on the standard output preceded by its line number. The program should have no built-on limit on how long a line it can handle.
>
> So I wrote the following program in C, but I'm not sure that it is doing what it is supposed to do. I verified the source code against the solution in the back of the book and I'm pasting here what the solution in the back of the book is.
>
> #include<stdio.h>
> #include<stdlib.h>
>
> int main(){
>
> int ch;
> int at_beginning = 1;
> int line = 0;
>
> while( (ch==getchar())!= EOF){

You want `=' instead of `==' here. (This may be the first time
I've seen the "equals/assign" mistake in this direction; usually, it's
using `=' where `==' is meant, not the other way around.)

--
Eric Sosman
lid

John <> writes:

> The program is supposed to read lines from the standard input, then each line is printed on the standard output preceded by its line number. The program should have no built-on limit on how long a line it can handle.
>
> So I wrote the following program in C, but I'm not sure that it is doing what it is supposed to do. I verified the source code against the solution in the back of the book and I'm pasting here what the solution in the back of the book is.
>
> #include<stdio.h>
> #include<stdlib.h>
>
> int main(){

int main(void) is better. It hardly matters for main, but for other
functions using the form with void will enable proper function prototype
checking so it's worth getting into the habit.

> int ch;
> int at_beginning = 1;
> int line = 0;
>
> while( (ch==getchar())!= EOF){

== confused with = already commented on.

> if(at_beginning == 1){

It's usually better to write:

if (at_beginning) { ...

> at_beginning = 0;
> line+=1;
> printf("%d ", line);
>
> }
>
> putchar(ch);
>
> if(ch == '\n')
> at_beginning = 1;

and here I'd write

at_beginning = ch == '\n';

This way the reader can see at once when at_beginning is 0 and when it
is 1. The earlier assignment becomes redundant.

> }
> return EXIT_SUCCESS;
> }

--
Ben.

In message <0.8a2a169873977757779c.20110130214737GMT.87k4hm5a iu.fsf@bsb.
me.uk>, Ben Bacarisse <> writes
>> if(at_beginning == 1){
>
>It's usually better to write:
>
> if (at_beginning) { ...

No it isn't

>> if(ch == '\n')
>> at_beginning = 1;
>
>and here I'd write
>
> at_beginning = ch == '\n';

Appalling! And dangerous.




--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

On 1/31/2011 4:05 AM, Chris H wrote:
> In message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
> me.uk>, Ben Bacarisse<> writes
>>> if(at_beginning == 1){
>>
>> It's usually better to write:
>>
>> if (at_beginning) { ...
>
> No it isn't

De gustibus non disputandum est.

>>> if(ch == '\n')
>>> at_beginning = 1;
>>
>> and here I'd write
>>
>> at_beginning = ch == '\n';
>
> Appalling! And dangerous.

Balderdash! And ignorant.

--
Eric Sosman
lid

In message <ii69dn$6vh$>, Eric Sosman
<> writes
>On 1/31/2011 4:05 AM, Chris H wrote:
>> In message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
>> me.uk>, Ben Bacarisse<> writes
>>>> if(at_beginning == 1){
>>>
>>> It's usually better to write:
>>>
>>> if (at_beginning) { ...
>>
>> No it isn't
>
> De gustibus non disputandum est.
>
>>>> if(ch == '\n')
>>>> at_beginning = 1;
>>>
>>> and here I'd write
>>>
>>> at_beginning = ch == '\n';
>>
>> Appalling! And dangerous.
>
> Balderdash! And ignorant.

The OP has already made one mistake with = and ==
The line is dangerous.

--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Chris H <> writes:

> In message <ii69dn$6vh$>, Eric Sosman
> <> writes
>>On 1/31/2011 4:05 AM, Chris H wrote:
>>> In message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
>>> me.uk>, Ben Bacarisse<> writes
>>>>> if(at_beginning == 1){
>>>>
>>>> It's usually better to write:
>>>>
>>>> if (at_beginning) { ...
>>>
>>> No it isn't
>>
>> De gustibus non disputandum est.
>>
>>>>> if(ch == '\n')
>>>>> at_beginning = 1;
>>>>
>>>> and here I'd write
>>>>
>>>> at_beginning = ch == '\n';
>>>
>>> Appalling! And dangerous.
>>
>> Balderdash! And ignorant.
>
> The OP has already made one mistake with = and ==
> The line is dangerous.

The original code (to which I was offering this alternative) has the
same set of operators so it would seem to offer the same opportunities
for =/== confusion. You also snipped my supporting argument. What is
your argument in support of the original (or against my alternative)?

--
Ben.

In message <0.c67692d26d53aa1f6676.20110131132623GMT.87ei7t5h mo.fsf@bsb.
me.uk>, Ben Bacarisse <> writes
>Chris H <> writes:
>
>> In message <ii69dn$6vh$>, Eric Sosman
>> <> writes
>>>On 1/31/2011 4:05 AM, Chris H wrote:
>>>> In message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
>>>> me.uk>, Ben Bacarisse<> writes
>>>>>> if(at_beginning == 1){
>>>>>
>>>>> It's usually better to write:
>>>>>
>>>>> if (at_beginning) { ...
>>>>
>>>> No it isn't
>>>
>>> De gustibus non disputandum est.
>>>
>>>>>> if(ch == '\n')
>>>>>> at_beginning = 1;
>>>>>
>>>>> and here I'd write
>>>>>
>>>>> at_beginning = ch == '\n';
>>>>
>>>> Appalling! And dangerous.
>>>
>>> Balderdash! And ignorant.
>>
>> The OP has already made one mistake with = and ==
>> The line is dangerous.
>
>The original code (to which I was offering this alternative) has the
>same set of operators so it would seem to offer the same opportunities
>for =/== confusion. You also snipped my supporting argument. What is
>your argument in support of the original (or against my alternative)?

Er what argument for it? There wasn't one.


--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Chris H wrote:
> In message
> <0.c67692d26d53aa1f6676.20110131132623GMT.87ei7t5h mo.fsf@bsb. me.uk>,
> Ben Bacarisse <> writes
>> Chris H <> writes:
>>
>>> In message <ii69dn$6vh$>, Eric Sosman
>>> <> writes
>>>> On 1/31/2011 4:05 AM, Chris H wrote:
>>>>> In
>>>>> message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
>>>>> me.uk>, Ben Bacarisse<> writes
>>>>>>> if(at_beginning == 1){
>>>>>>
>>>>>> It's usually better to write:
>>>>>>
>>>>>> if (at_beginning) { ...
>>>>>
>>>>> No it isn't
>>>>
>>>> De gustibus non disputandum est.
>>>>
>>>>>>> if(ch == '\n')
>>>>>>> at_beginning = 1;
>>>>>>
>>>>>> and here I'd write
>>>>>>
>>>>>> at_beginning = ch == '\n';
>>>>>
>>>>> Appalling! And dangerous.
>>>>
>>>> Balderdash! And ignorant.
>>>
>>> The OP has already made one mistake with = and ==
>>> The line is dangerous.
>>
>> The original code (to which I was offering this alternative) has the
>> same set of operators so it would seem to offer the same
>> opportunities for =/== confusion. You also snipped my supporting
>> argument. What is your argument in support of the original (or
>> against my alternative)?
>
> Er what argument for it? There wasn't one.

This one :
> This way the reader can see at once when at_beginning is 0 and when it
> is 1. The earlier assignment becomes redundant.

Bye, Jojo

In message <ii6ift$9k$>, Joachim Schmitz
<> writes
>Chris H wrote:
>> In message
>> <0.c67692d26d53aa1f6676.20110131132623GMT.87ei7t5h mo.fsf@bsb. me.uk>,
>> Ben Bacarisse <> writes
>>> Chris H <> writes:
>>>
>>>> In message <ii69dn$6vh$>, Eric Sosman
>>>> <> writes
>>>>> On 1/31/2011 4:05 AM, Chris H wrote:
>>>>>> In
>>>>>> message<0.8a2a169873977757779c.20110130214737GMT.8 7k4hm5aiu.fsf@bsb.
>>>>>> me.uk>, Ben Bacarisse<> writes
>>>>>>>> if(at_beginning == 1){
>>>>>>> It's usually better to write:
>>>>>>> if (at_beginning) { ...
>>>>>> No it isn't
>>>>> De gustibus non disputandum est.
>>>>>
>>>>>>>> if(ch == '\n')
>>>>>>>> at_beginning = 1;
>>>>>>> and here I'd write
>>>>>>> at_beginning = ch == '\n';
>>>>>> Appalling! And dangerous.
>>>>> Balderdash! And ignorant.
>>>> The OP has already made one mistake with = and ==
>>>> The line is dangerous.
>>> The original code (to which I was offering this alternative) has
>>>the
>>> same set of operators so it would seem to offer the same
>>> opportunities for =/== confusion. You also snipped my supporting
>>> argument. What is your argument in support of the original (or
>>> against my alternative)?
>> Er what argument for it? There wasn't one.
>
>This one :
>> This way the reader can see at once when at_beginning is 0 and when it
>> is 1. The earlier assignment becomes redundant.
>
>Bye, Jojo
>

So there is no argument to support it then and it is dangerous.





--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/