print "no" is an expression which returns 1 (print successful), and which prints no as a side effect. The (outer) print than has "yes", 1 as the argument list, so it prints yes1

The second example can be explained along the same lines: exit is evaluated before the print, and since it quits the program, the print isn't evaluated at all.

D:\>cat bob
$var=1;
print"yes",print"no" if ($var)



D:\>perl -MO=Deparse,-p bob
($var = 1);
($var and print('yes', print('no')));
bob syntax OK
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You have problems understanding where your argument lists end. It would help you to use parens around your arguments.

print"yes",print"no" if ($var);
means
print( "yes", print("no") ) if ($var);
1. The inner print outputs no.
2. The outer print outputs yes and the return value of the inner print (1 for success).

print"yes",exit ,print"no" if ($var);
means
print( "yes", exit(), print("no") ) if ($var);
Arguments are evaluated from left to right, so
1. "yes" is placed on the stack
2. exit is evaluated and causes perl to exit.
3. The inner print never gets to execute.
4. The outer print never gets to execute.

print"yes";exit ,print"no" if ($var);
means
print"yes";
exit(), print("no") if ($var);
Line breaks and the lack thereof are not significant to Perl, so
1. print("yes") is executed unconditionally.
2. exit is evaluated and causes perl to exit.
3. print("no") never gets to execute.

print"yes";print"no",exit if ($var);
means
print"yes";
print( "no", exit() ) if ($var);
1. print("yes") is executed unconditionally.
2. "no" is placed on the stack
3. exit is evaluated and causes perl to exit.
4. The second print never gets to execute.

1. print can take a list as an argument, thus the return value (1 ie. true) of the print"no" gets printed (comma is a list separator).
2. exit gets evaluated and your script exits.
3. The last part of your statement is evaluated first, that means that if( $var ) exit is executed first and it exits.

Update: corrected #2, thanks ikegami

exit evaluates given expression, your print statement in this case and exits.

No. exit is evaluated with no arguments in all of the OP's snippets.

print"yes",exit ,print"no" if ($var)
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is the same as

print( "yes", exit(), print("no") ) if ($var)
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That's because

print( "yes", exit( , print("no") ) ) if ($var)
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is illegal.

Ah, I stand corrected, I missed the comma :-)

--
seek $her, $from, $everywhere if exists $true{love};

Try it with these pragmas :

use strict;
use warnings;
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Update:
You may have a look at the ternary operator in perlop

my $var = 1;
print ($var ? 'yes' : 'no');
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hth,
PooLpi