Datediff

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DateDiff

Counts the years, months, days or other units between two date serials.

Syntax

Declare Function DateDiff ( ByRef interval As Const String, ByVal serial1 As Double, ByVal serial2 As Double, ByVal firstdayofweek As Long = fbUseSystem, ByVal firstdayofyear As Long = fbUseSystem ) As LongInt

Parameters

• interval
• date_serial1
• date_serial2
• firstdayofweek
• firstdayofyear

Description

interval is specified as follows:

value	interval
yyyy	years
q	quarter(three months)
m	months
w	seven day periods
ww	calendar weeks
d,y	days
h	hours
n	minutes
s	seconds

first_dayofweek Affects the counting when 'ww' interval is used.

value	first day of week	constant
omitted	sunday
0	local settings	fbUseSystem
1	sunday	fbSunday
2	monday	fbMonday
3	tuesday	fbTuesday
4	wednesday	fbWednesday
5	thursday	fbThursday
6	friday	fbFriday
7	saturday	fbSaturday

first_weekofyear specifies which year (previous or next) that the week which spans the end of one year and the beginning of the next should included with.

value	first week of year	constant
0	local settings	fbUseSystem
1	January 1's week	fbFirstJan1
2	first weeks having 4 days in the year	fbFirstFourDays
3	first full week of year	fbFirstFullWeek

Notice if you do an arithmetical subtraction of two date serials you get the difference in days.

The compiler will not recognize this function unless vbcompat.bi or datetime.bi is included.

Return Value

Returns a LongInt corresponding to the number of intervals found between two Date Serials.

If date_serial1 > date_serial2, the result is negative.

Remarks

Usage

#include "vbcompat.bi"

result = DateDiff( interval, date_serial1, date_serial2 [, firstdayofWeek [, firstweekofyear ] ] )

Differences from QB

• Did not exist in QB. This function appeared in Visual Basic.

Examples

#include "vbcompat.bi"

Dim s As String, d1 As Double, d2 As Double

Line Input "Enter your birthday: ", s

If IsDate( s ) Then

  d1 = DateValue( s )

  d2 = Now()

  Print "You are " & DateDiff( "yyyy", d1, d2 ) & " years old."

  Print "You are " & DateDiff( "d", d1, d2 ) & " days old."

  Print "You are " & DateDiff( "s", d1, d2 ) & " seconds old."

Else

  Print "Invalid date"

End If

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Category: Date and Time Functions
Kind: function

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.