5.27. Perl continue statement

发布时间 :2023-10-20 23:00:03 UTC      

Perl continue blocks are usually executed before the conditional statement is judged again.

continue statement can be used in the while and foreach in a loop.

5.27.1. Grammar #

while in circulation continue the syntax format of the statement isas follows:

while(condition){
   statement(s);
}continue{
   statement(s);
}

In foreach circulation , the continue syntax format of the statement is as follows:

foreach $a (@listA){
   statement(s);
}continue{
   statement(s);
}

Example #

while use in a loop continue statement:

Example #

#/usr/bin/perl$a=0;while($a<3){print"a =$a\\n";}continue{$a=$a+1;}

Execute the above program, and the output is as follows:

a = 0
a = 1
a = 2

foreach use in a loop continue statement:

Example #

#/usr/bin/perl@list=(1,2,3,4,5);foreach$a(@list){print"a
=$a\\n";}continue{lastif$a==4;}

Execute the above program, and the output is as follows:

a = 1
a = 2
a = 3
a = 4

Principles, Technologies, and Methods of Geographic Information Systems  102

In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress.