CFLib.org – Common Function Library Project

Description:
Compares two date ranges to determine if they overlap (or intersect) by one or more days. Returns true if the two ranges overlap.

Return Values:
Returns a boolean.

Example:

<cfset firstStart = createDate(2008, 8, 1)>
<cfset firstEnd = createDate(2008, 8, 31)>
<cfset secondStart = createDate(2008, 8, 4)>
<cfset secondEnd = createDate(2008, 8, 16)>

<cfif dateRangesOverlap( firstStart, firstEnd, secondStart, secondEnd )>
    The date ranges overlap. Do something here.
<cfelse>
    The two ranges do NOT overlap. Do something else.
</cfif>

Parameters:

Full UDF Source:

<!---
 Compares two date ranges to determine if they overlap by one or more days.
 
 @param start1      Initial date of the first range. (Required)
 @param end1      Ending date of the second range. (Required)
 @param start2      Initial date of the second range. (Required)
 @param end2      Ending date of the second range. (Required)
 @return Returns a boolean. 
 @author Leigh (cfsearching@yahoo.com) 
 @version 1, January 20, 2009 
--->
<cffunction name="dateRangesOverlap" returntype="boolean" output="false" hint="Returns true if two date ranges overlap by one or more days">
    <cfargument name="start1" type="date" required="true">
    <cfargument name="end1" type="date" required="true">
    <cfargument name="start2" type="date" required="true">
    <cfargument name="end2" type="date" required="true">
    <cfset var overlapFound = false>
    <cfset var datePart = "d">

    <cfif dateCompare(arguments.end1, arguments.start1, datePart) eq -1>
        <cfthrow message="End1 date cannot be earlier than start1 date">
    <cfelseif dateCompare(arguments.end2, arguments.start2, datePart) eq -1>
        <cfthrow message="End2 date cannot be earlier than start2 date">
    </cfif>
    <!--- first range starts within the second date range --->
    <cfif dateCompare(arguments.start1, arguments.start2, datePart) gte 0 and 
                dateCompare(arguments.start1, arguments.end2, datePart) lte 0>
        <cfset overlapFound = true>    
    <!--- first range ends within the second date range --->
    <cfelseif dateCompare(arguments.end1, arguments.start2, datePart) gte 0 and 
                dateCompare(arguments.end1, arguments.end2, datePart) lte 0>
        end between
        <cfset overlapFound = true>    
    <!--- first range spans the second date range --->
    <cfelseif dateCompare(arguments.start1, arguments.start2, datePart) lte 0 and 
                dateCompare(arguments.end1, arguments.end2, datePart) gte 0>
        spans        
        <cfset overlapFound = true>    
    </cfif>

    <cfreturn overlapFound>
</cffunction>