What is goto in Perl?
Goto statements in Perl help the program jump to another point in the code unconditionally. The new point can be anywhere within the same function.
Syntax
The goto statement makes the compiler jump to LABEL 1 in the syntax below. LABEL 1 is the user-defined identifier that indicates the target statement. The code block following the label is the destination.
LABEL 1:
## code block
#### .
# .
# .
## goto statement somewhere in the code block
goto LABEL 1;
Types of goto statements
There are three types of goto statements in Perl:
- Label:
Thegotostatement jumps to the statement marked as the label and continues execution from that statement. This type’s scope is limited. It can only work in the function in which it is called. - Expression:
We compute an expression that results in a label name to which the compiler jumps. - Sub-routine:
The compiler is transferred to the subroutine named here, which is called from within another subroutine. The target subroutine contains the destination code. We can also use this method for recursion.
Code
The code below demonstrates how we can use goto statements.
# Goto example# type 1: labels# function to print numbers from 1 to 10sub printNumbers_label(){my $num = 1;label_1:print "$num ";$num++;if ($num <= 10){goto label_1;}}# Driver Codeprint "Type 1: Label\n";printNumbers_label();# type 2: expressions# function to print numbers from 1 to 10sub printNumbers_2(){$a = "lab";$b = "el_2";my $num = 1;label_2:print "$num ";$num++;if ($num <= 10){# Passing Expression to label namegoto $a.$b;}}# Driver Codeprint "\nType 2: Expression\n";printNumbers_2();# type 3: subroutines# function to print numbers from 1 to 10sub label_3{print "$num ";$num++;if($num <= 10){goto &label_3;}}# Driver Codeprint "\nType 3: Subroutine\n";my $num = 1;label_3();
As explained in the types above:
- Type 1: The label takes execution directly to the code block which has the label as its name.
- Type 2: Expressions are computed before execution is taken to the block which has the computed name.
- Type 3: The execution is shifted to the mentioned subroutine.
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