1. For

For loop is used to iterate a set of statements based on a condition. Usually for loop is preferred when number of iterations are known in advance. In perl, for and foreach loops are interchangeable, and hence you can use foreach loop in where you use the for loop.

Syntax

for(Initialization; Condition; Increment/decrement){  
#code  
} 

#or

for (range){
  #code
}

Example

@x = (1..5);

print "Using For loop:\n";
for(@x){
 print("$_","\n");
}


print "\nUsing For-each loop:\n";
foreach(@x){
 print("$_","\n");
}

Both for and for-each loops produce same result.

Check Result here

Below example shows how to loop through hashes.

%nationalGame = (Australia=>'Cricket',
                 Japan => 'Wrestling',
                 NewZealand => 'Rugby',
                 USA => 'Baseball',
                 England => 'Cricket');

# Loop through hash elements
for(keys %nationalGame){
 print("National Game of $_ is $nationalGame{$_}\n");
}

Check result here

2. While

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations is not known in advance.

Syntax

while(condition){  
#code 
}  

Example

$i=1;
print "Using while loop:\n";
while ( $i <= 5) {
 print "$i\n" ;
  $i++;
}

Check result here

3. Do-while

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

Syntax

do{  
#code 
} while(condition); 

Example

$i=1;
print "Using do-while loop\n";
do {
  print"$i\n";
  $i++;
} while ($i<=5);

Check result here

4. Until

Until is just opposite of while loop and executes a block of code as long as the condition is false.

Syntax

until(conditional-expression){
   # code
}

Example

$i=1;
print "Using until loop:\n";
until ( $i > 5) {
 print "$i\n" ;
  $i++;
}

Check result here

5. Do-Until

Do-Until is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once and it executes a block of code as long as the condition is false.

Syntax

do{
   # code
}until(condition-expression)

Example

$i=1;
print "Using do-until loop\n";
do {
  print"$i\n";
  $i++;
} until ($i > 5);

Check result here