在这里,statement 1和statement 2是类 Sample 内的方法function的主体的组成部分。这些语句可以是任何有效的 Ruby 语句。例如,我们可以使用方法puts来输出Hello Ruby,如下所示: class Sample def hello puts "Hello Ruby!" end end 下面的实例将创建类 Sample 的一个对象,并调用hello方法: #!/usr/bin/ruby class...
我好像也忘了把它变成 if-statement,但我现在不必回到代码,而只需要插入点 (.) 并键入 if,这样就能用一个 if-statement 来包装这一行:“if picture.size> 5.megabytes”。 这项功能叫作“后缀代码补全”,允许您在不返回代码的情况下补充、更改或反转语句。 您可以使用 JavaScript 和 Ruby 在设置中查看所有后...
if true "if statement" # (译注:条件语句) elsif false "else if, optional" # (译注:可选的 else if 语句) else "else, also optional" # (译注:同样也是可选的 else 语句) end for counter in 1..5 puts "iteration #{counter}" end #=> iteration 1 #=> iteration 2 #=> iteration 3 #=...
statement2(); } 1. 2. 3. 4. 5. // 单条语句时也可以不使用大括号 if (cond) statement1(); // 把单条语句变为多条语句时忘记加大括号 if (cond) statement1(); statement2(); // 不出现语法错误 图1-19 单条语句和多条语句的问题 我不喜欢这种单条语句和多条语句的问题,所以想在自己的语言中...
if(mystring != null && mystring !="") 给String类增加一个新的方法 1 2 3 4 5 6 7 classString defNullOrEmpty? (self==nil||self=="") end end puts"test".NullOrEmpty? puts"".NullOrEmpty? Is this way cool? Yes. Is this very dangerous? Yes. Remember, Ruby is a chainsaw. ...
谚语是一个通常给出建议或表达生活真理的简短且富含智慧的陈述。A saying is a short wise statement that usually gives advice or expresses some truth about life.Many traditional sayings are still in general use today. Sometimes they are a great help if you need some wise words to express you ...
System info: The error message is: ruby-3.0.0 - #generating default wrappers... Error running 'run_gem_wrappers regenerate', please read /Users/stevewi/.rvm/log/1609273270_ruby-3.0.0/gemset.wrappers.default.log The compressed logs f...
Whenever you need to use someif / elsifstatements you could consider using a Ruby case statement instead. In this post, you will learn a few different use cases and how it all really works under the hood. Note: In other programming languages this is known as aswitchstatement. ...
Avoid long chains of&.. The longer the chain is, the harder it becomes to track what on it could be returning anil. Replace with.and an explicit check. E.g. if users are guaranteed to have an address and addresses are guaranteed to have a zip code: ...
sth = dbh.prepare(statement) sth.execute ... zero or more SQL operations ... sth.finish 这两种方法可用于传bind值给 SQL 语句。有时候被输入的值可能未事先给出,在这种情况下,则会用到绑定值。使用问号(?)替代实际值,实际值通过 execute() API 来传递。