fmt

• Documentation - https://pkg.go.dev/fmt
• Mainly used for
  • printing to console
  • formatting strings
  • reading user input

• Print, Println & printf

fmt.Print("Hello")  
fmt.Print("World")
// HelloWorld
 
fmt.Println("Hello")  
fmt.Println("World")
/*
Hello  
World
*/
 
fmt.Printf("Age: %d", 25)
// Age: 25

• printf formatters

  Verb	Meaning
  %v	Default value representation
  %+v	Struct with field names
  %#v	Go syntax representation
  %T	Type of value
  %d	Integer
  %f	Floating-point number
  %s	String
  %t	Boolean
  %p	Pointer address

• formatted string instead of printing.

msg := fmt.Sprintf("User: %s Age: %d", "John", 25)

• Formatted error

err := fmt.Errorf("invalid user id: %d", id)

• Reading
  • Scan - Reads input from console.
  • Scanln - Reads input until newline.
  • Scanf - Reads formatted input.

// scan with default space delimiter
var name string  
fmt.Scan(&name)
 
// scan with \n as delimiter
fmt.Scanln(&name)
 
// scan specific type
var age int  
fmt.Scanf("%d", &age)