This ProBuilder code snippet is designed to determine the last trading day of the current month, which can be particularly useful for trading strategies that require execution around month-end. The code consists of two parts: a main indicator and a helper function.

// Main Indicator: Calculate the last trading day of the current month
// Check if the year is a leap year
If Year Mod 4 = 0 And (Year Mod 100 <> 0 Or Year Mod 400 = 0) Then
    IsBisextil = 1
Else
    IsBisextil = 0
EndIf

// Define the number of days in February based on whether it is a leap year
if IsBisextil then
    feb=29
else
    feb=28
endif

// Determine the last day of the current month
if month=1 or month=3 or month=5 or month=7 or month=10 or month=12 then
    lastdayofmonth = call "#get_lastdayofmonth"[year,month,31]
elsif month=4 or month=6 or month=8 or month=9 or month=11 then
    lastdayofmonth = call "#get_lastdayofmonth"[year,month,30]
elsif month=2 then
    lastdayofmonth = call "#get_lastdayofmonth"[year,month,feb]
endif

return lastdayofmonth

// Helper Function: Adjust the last day of the month if it falls on a weekend
if myMonth >= 3 then
    D = (((23*myMonth)/9) + myDay + 4 + myYear + (myYear/4) - (myYear/100) + (myYear/400) - 2) mod 7
else
    z = myYear - 1
    D = (((23*myMonth)/9) + myDay + 4 + myYear + (z/4) - (z/100) + (z/400) ) mod 7
endif

lastday=myDay
if D=6 then
    lastday=myDay-1
elsif D=0 then
    lastday=myDay-2
endif

return lastday

The code is divided into two main sections:

• Leap Year Calculation: The code first checks if the current year is a leap year to determine the number of days in February.
• Month and Day Calculation: Based on the month, the code calls a helper function to find the last day of that month considering the number of days each month typically has. For February, it uses the previously determined day count based on whether it’s a leap year.
• Weekend Adjustment: The helper function “#get_lastdayofmonth” adjusts the last day if it falls on a weekend (Saturday or Sunday). This is crucial for trading strategies as markets are typically closed on weekends.

This snippet is useful for implementing trading strategies that need to execute trades at the end of the month, taking into account weekends when markets are closed.