empty blank

.nil? , .empty?, .blank? .present? 的区别 首先这三个都是判空的. 而 .nil? 和 .empty? 是ruby的方法. .blank? 是rails的方法 .nil?       判断对象是否存在(nil).不存在的对象都是nil的 .empty?  对象已经存在,判断是否为空字段,比如一个字符串是否为空串,或者一个数组中是否有值.有点像判断长度是否为零,呵呵 .blank?   相当于同时满足 .nil? 和 .empty? .railsAPI中的解释是如

ruby nil? empty? blank? 一句话区别: nil?与empty? 除了对象用nil?其他用empty?判断 ,blank?的用法几乎是前两者的结合体 nil?用于对象 object sky = nil sky.nil? # => true其他的对象的都为 object.nil? 都为false 如数据库的一个属性为空,则 属性.nil? # => true empty? 用于string 和 array 还有hash # Array [].empty? #=> tru

Keywords: Microsoft Excel, Office Excel, Shortcuts 1. Cell selection 1) Click a cell and drag mouse to select continious cells 2) Hold CTRL and click cells to select target cells 3) Go to a specified cell by entering its location in the Name Box. A10

1.字符串的扩展与修复 语言脚本都对字符串特别关注,有关的方法特别多,这些方法有三大类: 第一类:与标签无关的实现:charAt,charCodeAt,concat,lastIndexOf,localeCompare,match,replace,slice,split,substr,substring,toLocaleLowerCase,toLocalUpperCase,toLowerCase,toUpperCase以及从Object继承来的方法.如,toString,valueOf 第二类:与

LSL // Hello World in Linden Scripting Language (LSL) default { state_entry() { llSay(0, "Hello World"); } } Lua # Hello World in Lua print "Hello world" m4 # Hello World for the m4 macro processor Hello MACRO-10 TITLE HELLO WORLD ; HE

In Ruby, you check with nil? if an object is nil:article = nil article.nil? # => true empty? checks if an element - like a string or an array f.e. - is empty: # Array [].empty? #=> true # String "".empty? #=> true Rails adds the method 

In Ruby, you check with nil? if an object is nil: article = nil article.nil? # => true empty? checks if an element - like a string or an array f.e. - is empty: # Array [].empty? #=> true # String "".empty? #=> true Rails adds the method

article = nil article.nil? # => true empty? checks if an element - like a string or an array f.e. - is empty: # Array [].empty? #=> true # String "".empty? #=> true Rails adds the method blank? to the Object class: An object is blank if

Problem: the layout and src is empty after creating a new android project. Solution: choose "empty activity" instead of  "blank activity" when building a project step is creat activity.