Perl loop nesting
Perl language allows the use of another loop within one loop, and here are a few examples to illustrate this concept.
Grammar
Nesting for syntax of the loop statement:
for(init;condition;increment){for(init;condition;increment){statement(s);}statement(s);}
Nesting while syntax of the loop statement:
while(condition){while(condition){statement(s);}statement(s);}
Nesting do...while syntax of the loop statement:
do{statement(s);do{statement(s);}while(condition);}while(condition);
Nesting until the syntax of the loop statement:
until(condition){until(condition){statement(s);}statement(s);}
Nesting foreach syntax of the loop statement:
foreach$a(@listA){foreach$b(@listB){statement(s);}statement(s);}
Example
#!/usr/bin/perl$a=0;$b=0;# outer loop while($a<3){$b=0;#
Internal circulation while($b<3){print"a =$a, b =$b\\n";$b=$b+1;}$a=$a+1;print"a
=$a\\n\\n";}
Execute the above program, and the output is as follows:
a = 0, b = 0
a = 0, b = 1
a = 0, b = 2
a = 1
a = 1, b = 0
a = 1, b = 1
a = 1, b = 2
a = 2
a = 2, b = 0
a = 2, b = 1
a = 2, b = 2
a = 3