output all a* by searching a text file

[Umesh]

/*program to search a* in a text file & write output in a file.*
indicated any character*/

#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c[2];
for(int i=1;i<3;++i)
{
while((c[i]=getc(f))!=EOF)
if(c[1]=='a'&& c[2]!=' ')
fprintf(fp,"%c\ n",c[i]);
}
fclose(f);
fclose(fp);
return 0;
}
/*
INPUT c:/1.txt
abc
abc
abd
ap

OUTPUT c:/2.txt
a
a
a
a

REQUIRED OUTPUT c:/2.txt
ab
ab
ab
ap
*/

[Walter Roberson]

In article <11************ **********@n59g 2000hsh.googleg roups.com>,
Umesh <fr************ ****@gmail.comw rote:

>/*program to search a* in a text file & write output in a file.*
indicated any character*/

You didn't actually ask any question.

>
#include<stdio .h>
#include<stdli b.h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c[2];
for(int i=1;i<3;++i)
{
while((c[i]=getc(f))!=EOF)
if(c[1]=='a'&& c[2]!=' ')
fprintf(fp,"%c\ n",c[i]);
}

Consider what happens when i is 1. You've only read in the single
character, into c[1], but you then compare c[2] to ' ' even though
c[2] has not been given a value yet. Whatever value c[2] happens to
have, chances are that it isn't ' ', so if c[1] is 'a', the if() will
succeed and you would print out c[1] on a line by itself.

You haven't broken out of the while yet, so the while would continue,
still with i being 1, so you would read the next character into c[1],
compare it to 'a', and if it did happen to be an 'a', you would
again compare the uninitialized c[2] to ' ', probably succeeding.

If you have a look, you will see that you will not break out of this
loop until EOF, so this loop will keep scanning through the file
finding all 'a', printing them out on a line by themselves, and
continuing on.

Once EOF is finally reached, the while would terminate and the
next iteration of the for loop would execute, with i = 2.
This time, c[2] would be read into, but since we already hit EOF
we know that we are going to get EOF again, causing the while loop
to terminate. The for loop would terminate, and you'd
continue on with the rest of the program.

>fclose(f);
fclose(fp);
return 0;
}
/*
INPUT c:/1.txt
abc
abc
abd
ap

OUTPUT c:/2.txt
a
a
a
a

REQUIRED OUTPUT c:/2.txt
ab
ab
ab
ap
*/

Your specifications are unclear: what is supposed to happen if
you encounter an 'a' in the middle of a line?

By the way, what purpose did you have in mind when you wrote
the for() loop? What exactly is it that needs to be executed
a fixed number of times?
--
Programming is what happens while you're busy making other plans.

[Keith Thompson]

Umesh <fr************ ****@gmail.comw rites:

/*program to search a* in a text file & write output in a file.*
indicated any character*/

#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c[2];
for(int i=1;i<3;++i)
{
while((c[i]=getc(f))!=EOF)
if(c[1]=='a'&& c[2]!=' ')
fprintf(fp,"%c\ n",c[i]);
}
fclose(f);
fclose(fp);
return 0;
}

[snip]

Judicious use of white space would make your code *much* easier to
read.

Here's your program again. I've reformatted it for legibility, but
I've made no other changes.

/* program to search a* in a text file & write output in a file.*
indicated any character */

#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE *f, *fp;
f = fopen("c:/1.txt", "r");
if (f == NULL)
{
puts("Error opening file");
exit(0);
}
fp = fopen("c:/2.txt", "w");
char c[2];
for (int i=1; i<3; ++i)
{
while ((c[i] = getc(f)) != EOF)
if (c[1] == 'a' && c[2] != ' ')
fprintf(fp, "%c\n", c[i]);
}
fclose(f);
fclose(fp);
return 0;
}

--
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"

[Barry Schwarz]

On 15 May 2007 11:47:57 -0700, Umesh <fr************ ****@gmail.com>
wrote:

>/*program to search a* in a text file & write output in a file.*
indicated any character*/

#include<stdio .h>
#include<stdli b.h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c[2];

Definitions need to appear before statements unless you have a C99
compiler. There are only two elements of c: c[0] and c[1].

>for(int i=1;i<3;++i)
{
while((c[i]=getc(f))!=EOF)

If i ever exceeds one, this invokes undefined behavior by attempting
to evaluate a non-existent element of an array.

if(c[1]=='a'&& c[2]!=' ')

If c[1] is 'a', then this invokes undefined behavior by attempting to
evaluate the non-existent c[2].

fprintf(fp,"%c\ n",c[i]);
}
fclose(f);
fclose(fp);
return 0;
}
/*
INPUT c:/1.txt
abc
abc
abd
ap

OUTPUT c:/2.txt
a
a
a
a

REQUIRED OUTPUT c:/2.txt
ab
ab
ab
ap
*/

Remove del for email

[Barry Schwarz]

On Tue, 15 May 2007 19:46:22 +0000 (UTC), ro******@ibd.nr c-cnrc.gc.ca
(Walter Roberson) wrote:

>In article <11************ **********@n59g 2000hsh.googleg roups.com>,
Umesh <fr************ ****@gmail.comw rote:

>>/*program to search a* in a text file & write output in a file.*
indicated any character*/

You didn't actually ask any question.

>>
#include<stdi o.h>
#include<stdl ib.h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c :/2.txt","w");
char c[2];
for(int i=1;i<3;++i)
{
while((c[i]=getc(f))!=EOF)
if(c[1]=='a'&& c[2]!=' ')
fprintf(fp,"%c \n",c[i]);
}

Consider what happens when i is 1. You've only read in the single
character, into c[1], but you then compare c[2] to ' ' even though
c[2] has not been given a value yet. Whatever value c[2] happens to

It is very difficult to give c[2] a value since it doesn't exist.

>have, chances are that it isn't ' ', so if c[1] is 'a', the if() will
succeed and you would print out c[1] on a line by itself.

You haven't broken out of the while yet, so the while would continue,
still with i being 1, so you would read the next character into c[1],
compare it to 'a', and if it did happen to be an 'a', you would
again compare the uninitialized c[2] to ' ', probably succeeding.

If you have a look, you will see that you will not break out of this
loop until EOF, so this loop will keep scanning through the file
finding all 'a', printing them out on a line by themselves, and
continuing on.

Once EOF is finally reached, the while would terminate and the
next iteration of the for loop would execute, with i = 2.
This time, c[2] would be read into, but since we already hit EOF
we know that we are going to get EOF again, causing the while loop
to terminate. The for loop would terminate, and you'd
continue on with the rest of the program.

>>fclose(f);
fclose(fp);
return 0;
}
/*
INPUT c:/1.txt
abc
abc
abd
ap

OUTPUT c:/2.txt
a
a
a
a

REQUIRED OUTPUT c:/2.txt
ab
ab
ab
ap
*/

Your specifications are unclear: what is supposed to happen if
you encounter an 'a' in the middle of a line?

By the way, what purpose did you have in mind when you wrote
the for() loop? What exactly is it that needs to be executed
a fixed number of times?

Remove del for email

[Walter Roberson]

In article <d6************ *************** *****@4ax.com>,
Barry Schwarz <sc******@doezl .netwrote:

>On Tue, 15 May 2007 19:46:22 +0000 (UTC), ro******@ibd.nr c-cnrc.gc.ca
(Walter Roberson) wrote:

>>Consider what happens when i is 1. You've only read in the single
character, into c[1], but you then compare c[2] to ' ' even though
c[2] has not been given a value yet. Whatever value c[2] happens to

>It is very difficult to give c[2] a value since it doesn't exist.

Good point ;-) But does it make the behaviour any more undefined?
--
Is there any thing whereof it may be said, See, this is new? It hath
been already of old time, which was before us. -- Ecclesiastes

[Umesh]

/*WORKING BUT HOW TO GENERALISE IT FOR A LONG STRING
LIKE umesh*** ? */
#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c,ch;
while((c=getc(f ))!=EOF && (ch=getc(f))!=E OF )
{
if(c=='a'&& ch!=' ')
fprintf(fp,"%c% c\n",c,ch);
}
fclose(f);
fclose(fp);
return 0;
}
/* INPUT
abc
abc
abd
ap
OUTPUT
ab
ab
ab
ap
*/

[Mark F. Haigh]

On May 15, 10:50 pm, Umesh <fraternitydisp [e-mail] rote:

/*WORKING BUT HOW TO GENERALISE IT FOR A LONG STRING
LIKE umesh*** ? */
#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c,ch;
while((c=getc(f ))!=EOF && (ch=getc(f))!=E OF )
{
if(c=='a'&& ch!=' ')
fprintf(fp,"%c% c\n",c,ch);}

fclose(f);
fclose(fp);
return 0;}

>From your behavior here, you appear to be an idiot. You don't format

your code at all, and you don't ask any sensible, respectful, non-
homework questions.

You've already been given much more help than you deserve.

Mark F. Haigh
mf*****@sbcglob al.net

[Richard Heathfield]

Umesh said:

/*WORKING BUT HOW TO GENERALISE IT FOR A LONG STRING
LIKE umesh*** ? */
#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL) { puts("Error opening file");exit(0); }
fp=fopen("c:/2.txt","w");
char c,ch;
while((c=getc(f ))!=EOF && (ch=getc(f))!=E OF )

Working? Well, on my system, it doesn't even compile, of course, but if
we remove the dependency on mythical C99-conforming compilers, and if
we hack the filenames into something a bit more sensible, you're still
faced with the problem that you have the wrong types for c and ch, and
you are assuming that the opening of the output file works, which it
need not (when it failed on my system, the program dumped core).

And you still haven't learned about indentation.

None of the above crits is new to you. If you are unwilling to learn,
why do you bother to post queries here?

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[Umesh]

/*WORKING BUT HOW TO GENERALISE IT FOR A LONG STRING
LIKE umesh*** ? */
#include<stdio. h>
#include<stdlib .h>
int main(void)
{
FILE *f,*fp;
f=fopen("c:/1.txt","r");
if(f==NULL)
{
puts("Error opening file");
exit(0);
}
fp=fopen("c:/2.txt","w");
if(fp==NULL)
{
puts("Error opening file");
exit(0);
}
char c,ch;
while((c=getc(f ))!=EOF && (ch=getc(f))!=E OF )
{
if(c=='a'&& ch!=' ')
fprintf(fp,"%c% c\n",c,ch);
}
fclose(f);
fclose(fp);
return 0;
}
/* INPUT
abc
abc
abd
ap
OUTPUT
ab
ab
ab
ap
*/