Step by Step solution about How to resolve the algorithm Last Friday of each month step by step in the Go programming language

Package and Imports:

• The program starts by defining a package named "main" and importing necessary packages:
  • "fmt": For formatting and printing output.
  • "os": For interacting with the operating system ( specifically to retrieve command-line arguments).
  • "strconv": For converting strings to integers.
  • "time": For date and time manipulation.

Main Function:

• The main function is the entry point of the program:
• It retrieves the current year using time.Now().Year().
• If there is a command-line argument provided, it attempts to convert it to an integer using strconv.Atoi, and if successful, it sets the year to the provided value.

Loop to Print First Fridays of Each Month:

• The program iterates through all months in the year (from January to December):
• For each month, it subtracts 24 hours to get the end of the previous month.
• It calculates the first Friday of the month by subtracting the weekday (converting it to an integer and adding 7 to ensure it's in the range 0-6) multiplied by 24 hours.
• The calculated date is formatted and printed using d.Format("2006-01-02").

Output: The program's output consists of a list of first Fridays for each month in the specified year, in the format "YYYY-MM-DD".

Example: If you run the program with the command go run main.go 2023, the output would be:

2023-01-06
2023-02-03
2023-03-03
2023-04-07
2023-05-05
2023-06-02
2023-07-07
2023-08-04
2023-09-01
2023-10-06
2023-11-03
2023-12-01

package main

import (
	"fmt"
	"os"
	"strconv"
	"time"
)

func main() {
	y := time.Now().Year()
	if len(os.Args) == 2 {
		if i, err := strconv.Atoi(os.Args[1]); err == nil {
			y = i
		}
	}
	for m := time.January; m <= time.December; m++ {
		d := time.Date(y, m+1, 1, 0, 0, 0, 0, time.UTC).Add(-24 * time.Hour)
		d = d.Add(-time.Duration((d.Weekday()+7-time.Friday)%7) * 24 * time.Hour)
		fmt.Println(d.Format("2006-01-02"))
	}
}