1、 if(){} 2、 if(){}else {} 3、 if(){}elsif(){}else{} unless(){} (和if相反,if是条件成立执行,unless是条件不成立执行语句) 和if相同有1、2、3 switch语句 语法格式: use Switch; switch(argument){ case 1 { print "数字 1" } ...
system: Now you are a programming expert. I will ask you grammar questions and you will provide a comparison table of the syntax for Bash, Tcl, and Perl in markdown format based on my questions. Please reply in Chinese. Thank you. user: 变量 assistant: 注意:在 Bash 和 Tcl 中,变量名...
#!/usr/bin/perl $bar = "This is foo and again foo"; if ($bar =~ /foo/) { print "First time is matching\n"; } else { print "First time is not matching\n"; } $bar = "foo"; if ($bar =~ /foo/) { print "Second time is matching\n"; } else { print "Second time is...
还有一点值得注意的是Perl没有提供像C语言一样的 switch 叙述,不过Perl的pattern match的功能非常强,所以我建议你直接用 if else 叙述来做就好了。 3子程序(Subroutines) (a) Syntax: sub NAME {Code} (b) 呼叫子程序: &NAME(para1, para2,...) (c) 参数传递:@_ Perl 和C一样是采用Call by value的...
if (Expression) {Code Segment} else {Code Segment} if (Expression) {Code Segment} elsif (Expression) {Code Segment} else {Code Segment} # elsif 就是 else if # 如果指令(statement)只有一項,我們可以使用倒裝句法,看起來比較簡潔。 statement if (Expression); ...
else{ $has_found_bad_record=1; } 1.4数组和哈希 数组类型的变量采用复数,hash类型的变量采用单数。要用undef显式释放变量空间。 正确: my%option; my%title_of; my%count_for; my%is_available; #andlater... if($option{'count_all'}&&$title_of{$next_book}=~m/$target/xms){ ...
The else statement can be used with unless statement. It is used to execute block of codes whenever unless condition gives true result. Syntax unless(condition){ statements; } else { statements; } Flow Diagram: In the example below, else statement is used to print a message if the variable...
In the Template Toolkit, there are two main conditional directives: IF and SWITCH. In addition, there is the UNLESS directive, which is a negated IF. IF, ELSIF, ELSE, and UNLESS The primary directive for conditional execution is the IF statement. The basic syntax is: [% IF test %] ...
The any function has the same syntax as , accepting a block and a list of values, but it only returns true or false. True, if the block gives true for any of the values. False if none of them match. It also short circuits so on large lists this can be a lot faster. ...
else{ 所以条件表达式为假时的语句块; } Python: if 条件表达式1: 条件表达式1为真时的语句块 elif 条件表达式2: 条件表达式2为真时的语句块 else: 所以条件表达式为假时的语句块 【unless条件判断】 Shell:无 perl: unless(条件表达式){ 条件表达式为假执行的语句块; ...