Perl Learning Four: statements

Statement:
If/unless

While/foreach/do. While/for

1. Summary of true value of expression
Any expression has a true or false value: logical, String, list, file

2.if

if (expression1) {

statements;

}

else if (expression2) {

statements;

}

Else
{

statements;

}

3.unless (expression1)

{
Statement

}

4.while (expression1)
{

statements;

}

5.do{
statements;
}
while (expression1)

6.untile (expression1)
{

statements;

}

7.do
{
statements;
}
Untile (expression1)

8.for (EXPR1;EXPR2;EXPR3)
{
statements;
}

9.foreach $w (list, array) {statement}
$w Rich Meaning

General form:

foreach $a (@a) {}

foreach $a (1, 2, 3, 4) {}

foreach $k (keys%h) {}

foreach $a (@a) {}, loop variable default is $_

Print $_ variable value for printing

Perl Learning Four: statements