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Time format layout error using standard date

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BugFind the bug and fix the code

What it should do

Format time using year-month-day layout. Example: formatCustomDate(2026, 11, 9) -> "2026-11-09"

What happens instead

Output string produces corrupted date format like YYYY-MM-DD

package main

import (
	"fmt"
	"time"
)

func formatCustomDate(year, month, day int) string {
	t := time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.UTC)
	// Go does not use YYYY-MM-DD; it uses reference time 2006-01-02
	return t.Format("YYYY-MM-DD")
}

func main() {
	fmt.Println(formatCustomDate(2026, 11, 9))
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

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This bug belongs to the mutation and copying bugs pattern

Assignment does not copy, a shallow copy still shares its contents, and mutating methods return None.

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package main import ( "fmt" "time" ) func formatCustomDate(year, month, day int) string { t := time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.UTC) // Go does not use YYYY-MM-DD; it uses reference time 2006-01-02 return t.Format("YYYY-MM-DD") } func main() { fmt.Println(formatCustomDate(2026, 11, 9)) }

Time format layout error using standard date

What it should do

What happens instead

More mutation and copying bugs to practise

Time format layout error using standard date

What it should do

What happens instead

More mutation and copying bugs to practise