Perl | Arrays (push, pop, shift, unshift)

Perl provides various inbuilt functions to add and remove the elements in an array. 

Function	Description
push	Inserts values of the list at the end of an array
pop	Removes the last value of an array
shift	Shifts all the values of an array on its left
unshift	Adds the list element to the front of an array

push function

This function inserts the values given in the list at an end of an array. Multiple values can be inserted separated by comma. This function increases the size of an array. It returns number of elements in new array. 

Syntax: push(Array, list)

Example:

Perl

#!/usr/bin/perl

# Initializing the array
@x = ('Java', 'C', 'C++');

# Print the Initial array
print "Original array: @x \n";

# Pushing multiple values in the array
push(@x, 'Python', 'Perl');

# Printing the array
print "Updated array: @x";

Output:

Original array: Java C C++ 
Updated array: Java C C++ Python Perl

pop function

This function is used to remove the last element of the array. After executing the pop function, size of the array is decremented by one element. This function returns undef if list is empty otherwise returns the last element of the array. 

Syntax: pop(Array)

Example:

Perl

#!/usr/bin/perl

# Initializing the array
@x = ('Java', 'C', 'C++');

# Print the Initial array
print "Original array: @x \n";

# Prints the value returned by pop
print "Value returned by pop: ", pop(@x);

# Prints the array after pop operation
print "\nUpdated array: @x";

Output:

Original array: Java C C++ 
Value returned by pop: C++
Updated array: Java C

shift function

This function returns the first value in an array, removing it and shifting the elements of the array list to the left by one. Shift operation removes the value like pop but is taken from the start of the array instead of the end as in pop. This function returns undef if the array is empty otherwise returns first element of the array. 

Syntax: shift(Array)

Example:

Perl

#!/usr/bin/perl

# Initializing the array
@x = ('Java', 'C', 'C++');

# Print the Initial array
print "Original array: @x \n";

# Prints the value returned
# by shift function
print "Value returned by shift: ",
                        shift(@x);

# Array after shift operation
print "\nUpdated array: @x";

Output:

Original array: Java C C++ 
Value returned by shift :Java
Updated array: C C++

unshift function

This function places the given list of elements at the beginning of an array. Thereby shifting all the values in an array by right. Multiple values can be unshift using this operation. This function returns the number of new elements in an array. 

Syntax: unshift(Array, List)

Example:

Perl

#!/usr/bin/perl

# Initializing the array
@x = ('Java', 'C', 'C++');

# Print the Initial array
print "Original array: @x \n";

# Prints the number of elements
# returned by unshift
print "No of elements returned by unshift: ",
                   unshift(@x, 'PHP', 'JSP');

# Array after unshift operation
print "\nUpdated array: @x";

Output:

Original array: Java C C++ 
No of elements returned by unshift :5
Updated array: PHP JSP Java C C++