Re: New student, can we write this program in perl...

[choroba]

Hallo rahulraina7, wellcome to the Monastery.

This is not a code writing service. Can you show how you would solve the problem in C? We can then describe what changes you should do to the code to translate it to Perl.

[rahulraina7]

Thank you Choroba Sir for your interest , please have a look at C code.

#include<stdio.h>
#include<conio.h>
void main()
{
int a[20],b[20],c[20],i,j=0,k=0,n;
clrscr();
printf("Enter the number of elements");
scanf("%d",&n);
printf("Enter  n numbers\n");
for(i=0;i<n;i++)
{
scanf("%d",&a[i]);
}
for(i=0;i<n;i++)
{
if((a[i]%2)==0)
{
b[j]=a[i];
j++;
}
else
{
c[k]=a[i];
k++;
}
}
printf("The  even numbers  are\n");
for(i=0;i<j;i++)
{
printf("%d\n",b[i]);
}
printf("The odd numbers are\n");
for(i=0;i<k;i++)
{
printf("%d\n",c[i]);
}
getch();
}

It will basically input an array of 'n' numbers and then separate it into two arrays, one contains odd numbers and one contains even numbers. Hoping to hear from you soon.

[choroba]

I would change your program to this one:

#!/usr/bin/perl
use warnings;
use strict;

print 'Enter the number of elements: ';
my $n = <>;                                     # Read the input.
chomp $n;                                       # Remove the newline.
print "Enter $n numbers.\n";
my @a;
for (1 .. $n) {
    push @a, scalar <>;                         # Push numbers to the 
+array.
}
chomp @a;                                       # Remove the newlines.

print join (' ', 'The even numbers are:',
                 grep $_ % 2, @a),              # grep filters the num
+bers = 1 modulo 2
      "\n";
print join (' ', 'The odd numbers are:',
                 grep 1 - $_ % 2, @a),
      "\n";

Not really similar, is it? The main differences:
• No main function needed.
• Variables are declared where needed.
• The diamond operator is used to read from the input.
• for can be used with simpler syntax, avoiding off by 1 errors (see perlsyn)
• grep can be used to filter arrays. No need for temporary variables to keep the results if you do not need them later.

[Jenda]

use strict;
# #include<conio.h>
#void main()
#{
my (@a,@b,@c,$i,$j,$k,$n);

print("Enter the number of elements\n");
$n = <>;
printf("Enter  %d numbers\n",$n);
for($i=0;$i<$n;$i++)
{
  push @a, scalar(<>);
}
for($i=0;$i<$n;$i++)
{
  if(($a[$i]%2)==0)
  {
    $b[$j]=$a[$i];
    $j++;
  }
  else
  {
    $c[$k]=$a[$i];
    $k++;
  }
}
print("The  even numbers  are\n");
for($i=0;$i<$j;$i++)
{
printf("%d\n",$b[$i]);
}
printf("The odd numbers are\n");
for($i=0;$i<$k;$i++)
{
 printf("%d\n",$c[$i]);
}
<>;
#}

Not that this was the best (or even just a particularly good) way to write this, but it's the minimal change. Huge difference from the C code, right?