判断参数是否为空.此方法可以判断数组/结构/query/一般变量

<cfscript>
/**
 * Check if a variable is set and has a value.
 * Mods by RCamden to add support for struct/query
 *
 * @param varName   Variable to check for. (Required)
 * @return Returns a boolean.
 * @author Fabio Serra (faser@faser.net)
 * @version 1, July 10, 2003
 */
function isEmpty(varName) {
 var ptr = "";
 
 if(not isDefined(varName)) return true;
 ptr = evaluate(varName);
 
 if(isSimpleValue(ptr)) {
  if(not len(ptr)) return true;
 } else if(isArray(ptr)) {
  if(arrayIsEmpty(ptr)) return true;
 } else if(isStruct(ptr)) {
  if(structIsEmpty(ptr)) return true;
 } else if(isQuery(ptr)) {
  if(not ptr.recordCount) return true;
 }
  
 return false;
}
</cfscript>

<cfset myVar = 1>
<cfset myVar3 = arrayNew(1)>
<cfset myVar4 = arrayNew(1)>
<cfset myVar4[1] = "e">
<cfset myVar5 = structNew()>
<cfset myVar6 = structNew()>
<cfset myVar6.name = "ray">
<cfset myVar7 = queryNew("F")>
<cfset myVar8 = queryNew("F")>
<cfset queryAddRow(myVar8,1)>

<cfoutput>
IsEmpty("myvar") = #isEmpty("myVar")#<br>
IsEmpty("myvar2") = #isEmpty("myVar2")#<br>
IsEmpty("myvar3") = #isEmpty("myVar3")#<br>
IsEmpty("myvar4") = #isEmpty("myVar4")#<br>
IsEmpty("myvar5") = #isEmpty("myVar5")#<br>
IsEmpty("myvar6") = #isEmpty("myVar6")#<br>
IsEmpty("myvar7") = #isEmpty("myVar7")#<br>
IsEmpty("myvar8") = #isEmpty("myVar8")#<br>
</cfoutput>

<cfif isEmpty("myVar")>
<cfset myVar = "Pippo">
</cfif>