Perl goto statement

Author：Eve Cole Update Time：2025-01-03 10:48:01

Perl has three goto forms: got LABLE, goto EXPR, and goto &NAME:

serial number	goto type
1	goto LABEL Find the statement marked LABEL and re-execute it from there.
2	goto EXPR The goto EXPR form is just the general form of goto LABEL. It expects the expression to generate a tag name and jumps to that tag for execution.
3	goto&NAME It replaces the running child process with a call to the named child process.

grammar

The syntax format is as follows:

 goto LABEL or goto EXPR or goto &NAME

flow chart

Example

The following two examples jump out of the output when the variable $a is 15.

The following is a commonly used goto example:

Example

#/usr/bin/perl $a = 10 ; LOOP : do { if ( $a == 15 ) { # Skip iteration $a = $a + 1 ; # Use goto LABEL form print " Jump out of output n " ; goto LOOP ; print " This sentence will not be executed n " ; } print " a = $a n " ; $a = $a + 1 ; } while ( $a < 20 ) ;

Executing the above program, the output result is:

 a = 10a = 11a = 12a = 13a = 14 jump out of the output a = 16a = 17a = 18a = 19

The following examples use the goto EXPR form. We used two strings and linked them using a period (.).

Example

$a = 10 ; $str1 = " LO " ; $str2 = " OP " ; LOOP : do { if ( $a == 15 ) { # Skip iteration $a = $a + 1 ; # Use goto EXPR form goto $str1 . $str2 ; # Similar to goto LOOP } print " a = $a n " ; $a = $a + 1 ; } while ( $a < 20 ) ;

Executing the above program, the output result is:

 a = 10a = 11a = 12a = 13a = 14a = 16a = 17a = 18a = 19