无涯教程-Perl - if...elsif...else语句函数

if 语句后可以跟可选的 elsif ... else 语句，这对于使用单个if ... elsif语句测试各种条件非常有用。

if...elsif...else - 语法

Perl编程语言中的 if ... elsif...else语句的语法是-

if(boolean_expression 1) {
   # Executes when the boolean expression 1 is true
} elsif( boolean_expression 2) {
   # Executes when the boolean expression 2 is true
} elsif( boolean_expression 3) {
   # Executes when the boolean expression 3 is true
} else {
   # Executes when the none of the above condition is true
}

if...elsif...else - 示例

#!/usr/local/bin/perl
 
$a=100;
# check the boolean condition using if statement
if( $a  ==  20 ) {
   # if condition is true then print the following
   printf "a has a value which is 20\n";
} elsif( $a ==  30 ) {
   # if condition is true then print the following
   printf "a has a value which is 30\n";
} else {
   # if none of the above conditions is true
   printf "a has a value which is $a\n";
}

在这里，我们使用等于运算符==，用于检查两个操作数是否相等。如果两个操作数相同，则返回true，否则返回false。

a has a value which is 100

参考链接

https://www.learnfk.com/perl/perl-if-elsif-statement.html