VBScript - Working With Date Values

Basics

Objects and Functions for Working With Date Values

Getting Current Date

Getting Tomorrow’s and Yesterday’s Dates

Comparing Dates

Calculating the Year and Month Duration

Encoding and Decoding Date Values

Modifying Date Values

Dealing with Week Days

When writing scripts we often deal with dates. There are certain date value formats and TestComplete routines that help handle dates.

Since the TestComplete scripting engine only supports OLE-compatible data types, the date-time values are implemented as floating-point variant values in a special format. The integer part of this value represents the number of days that have passed since December 30, 1899. The number after the decimal separator represents the fraction of a 24-hour period that has elapsed. However, you do not have to understand what these floating-point values represent. TestComplete provides several routines that help you convert these values to their string representation (see below).

Below are some examples of date-time values and their meaning:

When you are only working with date values the fractional part can be omitted.

TestComplete has the aqDateTime object that contains methods that can be useful when operating with dates.

One more object, aqConvert, provides methods to convert strings between date values and their string equivalents:

The aqDateTime and aqConvert objects are available for all supported scripting languages, so that you can use them to operate with date values regardless of the chosen language.

There are two routines that return current date: Today and Now. The difference between them is that the value returned by the Now routine includes both the date and time parts, whereas the Date routine returns only the date part. The script below demonstrates how to use them.

The samples below demonstrate how the aqDateTime object can be used to calculate tomorrow's date. The current date is obtained via the aqDateTime.Today method. Then the current date value is incremented via the aqDateTime.AddDays method. The DateTimeToStr method of the aqConvert object is used to convert the date value to a string that is posted to the TestComplete log.

In a similar way you can calculate any date that differs from the current day by a certain number of days: yesterday, the next or previous week and so on. For example to get yesterday’s date, you have to pass the -1 value to the aqDateTime.AddDays method as the second (Days) parameter.

To compare date/time values, use the aqDateTime.Compare method rather than comparison operators (like =, >, <, <> and others) provided by the scripting engine:

Generally there are 365 days in a calendar year. However the length of an astronomical year is about 365.242375 days, so in the course of time the fractional part would result in an extra day and the calendar year would lag from the astronomical. To avoid this the leap year that is 366 days long was invented.

The Gregorian calendar is the current standard calendar in most of the world and it adds a 29th day to February in all years evenly divisible by 4, except for centennial years (those ending in -00), which only receive the extra day if they are evenly divisible by 400. The aqDateTime object has a special method ,IsLeapYear, that accepts the year number and returns true if the specified year is a leap year. We can use this method to get the exact number of days in the desired year:

Using the IsLeapYear method we can get the number of days in the month. For all months, except February, the duration of a month is fixed and is either 30 or 31 days. The duration of February is 28 or 29 days depending on whether the current year is a leap year or not. The routine that gets the month duration would be the following:

Since date values are represented as variants, special routines are required that convert a variant value to a calendar date format and backwards. These operations are performed by the SetDateElements, GetYear, GetMonth and GetDay methods of the aqDateTime object. These methods take into account whether the current year is a leap year and the number of days in a month to guarantee that the value is valid. SetDateElements accepts the parts of a date and returns a variant date value.

The GetYear, GetMonth and GetDay methods perform a contrary operation: they accept a variant date/time value and return respective date parts of that value. Here is an example of how to use these routines:

Despite the fact that date/time values are represented as floating-point numbers, you cannot explicitly use ordinary arithmetic operators to change dates or time. However, the aqDateTime scripting object provides a number of methods that were designed to modify date/time values. These methods are: AddMonths, AddDays and AddTime. The AddTime method allows you to modify date and time portions at once.

As it is said above, these methods are used both for incrementing and decrementing date/time values. If a positive number is passed as Month, Days or as another parameter, the resulting value is increased. If the parameter is negative, the resulting value is decreased.

These methods take into account the number of days in the month, whether the year is a leap year and other aspects of time calculations, that is why the resulting value is guaranteed to be valid.

The code below demonstrates how to use these methods:

Besides recognizing the date, month and year, you may need to know which day of the week a certain date is. The aqDateTime.GetDayOfWeek method can help you do this. It accepts a variant date and returns the number of the week day that corresponds to it. The returned number ranges from 1 to 7, where 1 corresponds to Sunday, 2 - to Monday, and so on. The sample code below obtains the current date, calculates the day of the week and posts the name of the day to the log.

In addition to the day of the week, we can find out the week boundaries that the specified date belongs, that is, calculate the dates that the week starts and ends. This could be done using the following two routines. Here the number of a week day is subtracted from the specified date to get the beginning of a week, and to get the end of the week, six days are added to the calculated date.

Another frequent operation when dealing with dates is calculating the number of weeks that have passed since the beginning of the year. First we should clarify what week should be considered as the first week of a year. According to the ISO 8601 standard, the first week of a year is a week with the majority (four or more) of days in the starting year. In our case it is better to use another equivalent definition of the first week: the week with the date, January, 4th.

Here is the routine that calculates the week number in compliance with this rule. It accepts the date that belongs to the desired week, determines the end of this week and the end of the week that includes January 4, and that calculates the week number as the difference between those two values divided by 7.

Sometimes it is useful to know what day of the week the desired month starts or ends. The routines below return the week day number that correspond to the beginning and end of the month. They only have one input parameter that specifies the date which belongs to the desired month. If the parameter is missing then the routines return the results for the current month. The routines are similar to calculating the beginning and end of a week, but instead of the week day number, the day of the month number is used.