Re: simulation of a "wc" command

On 2008-08-29, s.dhilipkumar@xxxxxxxxx <s.dhilipkumar@xxxxxxxxx> wrote:
Hi

I have never done this excersice, this is just my version of
code. :) i have just checked few basic conditions and it imitates wc
to an extent.

#include<stdio.h>

char find_char(char x)
{
if( '\n' == x)
return 1;
if( ' ' == x)
return 2;
else
return 3;
}


This function can probably be replaced by the standard function
isspace() given in <ctype.h>.


int main(int argc, char* argv[])
{
FILE *fp=NULL;
char prev=0,ch,ctyp;
int wc=0,nl=0,ws=0;
if (argc != 2)
{
printf ("invlid argument \n");
return 1;
}

1 is not guaranteed to be a valid return value from main(). Use
EXIT_FAILURE from <stdlib.h> instead.

fp=fopen(argv[1], "r");
if (fp == NULL)
{
printf("Unable to open the file %s\n",argv[1]);
return 1;
}
while(!feof(fp))

Uh-oh. This will cause a fencepost error - instead, check ch
against EOF (and define it as an int, not a char, to hold this
value) and use feof() to confirm that it really was end-of-file,
not another error.

{
ch = fgetc(fp);
ctyp = find_char(ch);
if(ctyp == 1)

Yuck. Better to explicitly compare ch against ' ' or '\n',
whichever one you meant. Magic numbers are Bad News.

{
if ( prev == 3 )
wc++;nl++;
}
else if(ctyp == 2)
{
if(prev == 3)
wc++;
ws++;
}

This logic looks like I could replace it with the simpler:

if(isspace(ch))
++wc;

while(isspace(ch))
{
if(ch == '\n')
++nl;
++ws;
ch = fgetc(fp);
}

which is clearer IMHO.


Also, don't top-post. Your reply belongs below the text.

--
Andrew Poelstra apoelstra@xxxxxxxxxxxxxx
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