Perl 中的unless-else语句

Perl 中的unless-else语句，类似于unless 语句，Perl 中的unless-else语句与if-else 语句相反。在except-else中，如果条件为false，执行内部语句，如果条件为true，则执行else内的语句。

unless(condition) {
   #These statements would execute
   #if the condition is false.
   statement(s);
}
else {
   #These statements would execute
   #if the condition is true.
   statement(s);
}

示例如下：

#!/usr/local/bin/perl

printf "Enter any number:";
num = <STDIN>;
unless(num>=100) {
   #This print statement would execute,
   #if the given condition is false
   printf "num is less than 100\n";
}
else {
   #This print statement would execute,
   #if the given condition is true
   printf "number is greater than or equal to 100\n";
}

输出：

Enter any number:100
number is greater than or equal to 100