while(<INFILE>){    
    $_ =~ s/$searchPattern1/$repalcePattern1/g;
    $_ =~ s/$searchPattern2/$replacePattern2/g;
    $_ =~ s/$searchPattern3/$replacePattern3/g;
    print OUTFILE $_;
} # end while

##</code><code>##

if ($_ == s/$searchPattern1/){
 print("$searchPattern1 replaced with $replacePattern1 \n");
}elsif ($_ == s/$searchPattern2/){
 print("$searchPattern2 replaced with $replacePattern2 \n");
}elsif ($_ == s/$searchPattern3/){
 print("$searchPattern3 replaced with $replacePattern3 \n");
}else{
 print("Search Patterns not found");
} 

##</code><code>##

while(<INFILE>){
 if ($_ == s/$searchPattern1/){
  $_ =~ s/$searchPattern1/$repalcePattern1/g;
  print("$searchPattern1 replaced with $replacePattern1\n");
 }elsif ($_ == s/$searchPattern2/){
  $_ =~ s/$searchPattern1/$repalcePattern1/g;
  print("$searchPattern2 replaced with $replacePattern2\n");
 }elsif ($_ == s/$searchPattern3/){
  $_ =~ s/$searchPattern1/$repalcePattern1/g;
  print("$searchPattern3 replaced with $replacePattern3\n");
 }else{
   print("Search Patterns not found");
 }
 print OUTFILE $_;
} # end while 

##</code><code>##

<SOURCEFILE>
foo bar         <\n>
foobar    <\n>
BlahBlah Blah             <\n>

to:

foo bar<\n>
foobar<\n>
BlahBlah Blah<\n>