package main import "fmt" func formatFileSize(b int64) string { const unit = 1000 if b < unit { return fmt.Sprintf("%d B", b) } div, exp := int64(unit), 0 for n := b / unit; n >= unit; n /= unit { div *= unit exp++ } return fmt.Sprintf("%.0f %cB", float64(b)/float64(div), "KMGTPE"[exp]) }