empty set：数学里面集合术语 空集；空集合。专业术语解释：空集(empty set):约定存在一个没有任何元素的集合,称为空集,记为φ,有时也用{} 来表示.按子集的定义,空集是任何集合的子集。相关短语：axiom of empty set 空集公理 axiom of the empty set 空集公理 non-empty set 非空集 ; 非空集合...
empty set ( null set) A set that contains no elements. For example,if A={the odd numbers in the group 2,4}, then A has no elements in it, and is considered an empty set.An empty set is designated with the symbol ∅.Since an empty set has no elements in it, the empty set ...
* @param css the CharSequences to check, may be null or empty * @return{@codetrue}ifany of the CharSequences are empty or null * @since 3.2 */ public static boolean isAnyEmpty(final CharSequence... css) { if(Array...
empty:只要变量是否为 "" 或者 0 ,或者是 false 和 null ,都会返回 true ;isset:是判断变量是否存在,只要你这个变量不是 null 或未赋值,返回结果都是 true ;...isset($_GET['a']); //如果得不到变量a的值echo empty($_GET['a']); /...
CollectionView collectionView =newCollectionView { EmptyView ="No items to display"}; collectionView.SetBinding(ItemsView.ItemsSourceProperty,"EmptyMonkeys"); 结果是,由于数据绑定集合为null,因此将显示设置为EmptyView属性值的字符串: 当数据不可用时显示视图 ...
* @return {@code true} if the CharSequence is null, empty or whitespace * @since 2.0 * @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence) */publicstaticbooleanisBlank(final CharSequence cs){int strLen;if(cs==null||(strLen=cs.length())==0){returntrue;}for(int ...
一个对象,包含空模板的自定义内容。 默认值为null,指示未设置此属性。 属性 BrowsableAttributePersistenceModeAttributeTemplateContainerAttribute 示例 以下示例演示如何为空模板定义自定义模板。 ASP.NET (C#) <%@Pagelanguage="C#"%><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://...
IsEmptyreturnsTrueif the variable is uninitialized, or is explicitly set to Empty; otherwise, it returnsFalse.Falseis always returned ifexpressioncontains more than one variable. The following example uses theIsEmptyfunction to determine whether a variable has been initialized: ...
AITemplatethat contains the custom content for the empty data row. The default value isnull, which indicates that this property is not set. Attributes BrowsableAttributePersistenceModeAttributeTemplateContainerAttribute Examples The following code example demonstrates how to use theEmptyDataTemplateproperty to...
(in 1.4 it was just an empty parameter set) since that argument is only supposed to be a dictionary or list of dictionaries in 2.0. so if you send an empty list, that means you dont actually want to run an INSERT. should raise, however for connection, I dont think we could change ...