Date & Time Calculations

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Date & Time Calculations

DTO.SubtractHours - Subtract Hours from a Time

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MiniRobotLanguage (MRL)

 

DTO.SubtractHours Command

Subtract a Number of Hours from a Time

 

Intention

 

The DTO.SubtractHours command calculates a new time by subtracting a specified number of hours from a given time string. It correctly handles "time rollovers," where subtracting hours crosses midnight into the previous day.

 

This is useful for calculating start times based on an end time and duration, converting time zones, or scheduling events that need to occur a certain number of hours before a deadline. The command simplifies time arithmetic by managing the complexities of 24-hour time cycles automatically.

 

Syntax

 

DTO.SubtractHours|time|hours|[format]|[$$RES]

 

Parameter Explanation

 

time - The source time string from which hours will be subtracted (e.g., "14:00:00").

 

hours - The number of hours to subtract. This should be a positive integer.

 

format - (Optional) The format of the `time` string and the desired output format. Defaults to "HH:MM:SS" if omitted.

 

$$RES - (Optional) The variable to receive the resulting time string.

 

Example

 

'**********************************************

' DTO.SubtractHours - Sample

'**********************************************

'

' --- Sample 1: Subtract 4 hours from an afternoon time ---

$$TMA = "15:30:00"

DTO.SubtractHours|$$TMA|4|$$RES

MBX.15:30 minus 4 hours is: $$RES ' Result: 11:30:00

'

' --- Sample 2: Subtract hours crossing midnight ---

$$TMB = "02:15:00"

DTO.SubtractHours|$$TMB|5|$$RES

MBX.02:15 minus 5 hours is: $$RES ' Result: 21:15:00

'

' --- Sample 3: Using a custom time format ---

$$TMC = "01.00"

DTO.SubtractHours|$$TMC|2|HH.MM|$$RES

MBX.01.00 minus 2 hours is: $$RES ' Result: 23.00

ENR.

 

Remarks

 

The command returns only the resulting time. It does not provide information about the date, even if the calculation crosses a day boundary.

 

Limitations:

 

Requires a valid time string in the specified (or default) format. Malformed time strings will cause a parameter error.

 

See also:

 

•     DTO. - Date Time Operations

•     DTO.Add Hours

•     DTO.Add To Current Time

•     DTO.Time Diff

•     DTC. - Date and Time Calculation