learning-golang

Comments

• line comment //
• multiple lines comment /* */

---

Data Types

• boolean

  var b1 bool = true
  // or
  b1 := false

• string

  var str string = "hello world"
  // or
  str := "Hello"

• int - Signed Integers (uses first bit to identify either the sign + or -) (0 for + and 1 for -)

  • int: Depends on platform ; 32 bits in 32 bit systems and 64 bit in 64 bit systems

    var num int = 1234

  • int8: 8 bits: -128 to 127

    var num int8 = 127

  • int16 16 bits: -32768 to 32767

    var num int16 = 32767

  • int32 32 bits: -2147483648 to 2147483647

    var num int32 = -2147483648

  • int64 64 bits: -9223372036854775808 to 9223372036854775807

    var num int64 = -9223372036854775808

• uint - Unsigned Integers (not use any bit to identify either the sign + or -)

  • uint: Depends on platform ; 32 bits in 32 bit systems and 64 bit in 64 bit systems

    var num int = 1234

  • uint8: 8 bits: 0 to 255

    var num uint8 = 255

  • uint16: 16 bits: 0 to 65535

    var num uint16 = 65535

  • uint32: 32 bits: 0 to 4294967295

    var num uint32 = 4294967295

  • uint64: 64 bits: 0 to 18446744073709551615

    var num uint64 = 18446744073709551615

• float

  • float32: 32 bits: -3.4e+38 to 3.4e+38

    var num float32 = 3.4e+38

  • float64: 64 bits: -1.7e+308 to +1.7e+308

    var num float64 = 1.7976931e+308

---

Variables

• declare a variable with a specific type

  var x int = 8

• declare a variable and the type will be inferred

  x := "Islam"

• declare a variable without a value

  var x int

• declare multiple variables with the same type

  var x, y, z int = 1, 2, 3

• declare multiple variables with different types

  var a, b = 6, "hello"

• declare multiple variables with different types and the type will be inferred

  c, d := 7, "world"

• declare multiple variables in a block

  var (
    a int
    b int = 1
    c string = "hello"
  )

---

Constants

• declare a constant variable and the type will be inferred

  const PI = 3.14

• declare a constant variable with specific type

  const PI float32 = 3.14

---

Output functions

• Print function inserts a space between the arguments if neither are strings

  fmt.Print("hello world")
  
  // output
  hello world%

• Println function function prints its arguments and add a whitespace is between them, and a newline at the end

  fmt.Println("hello world")
  
  // output
  hello world

• Printf function formats its argument based on the given formatting verb
  • %v is used to print the value of the arguments

    var name = "Islam"
    fmt.Printf("hello %v", name)
    
    // output
    hello Islam%

  • %T is used to print the type of the arguments

    var name = "Islam"
    fmt.Printf("hello %T", name)
    
    // output
    hello string%

---

Arrays

• Array declaration

  var arr = [4]int{1, 2, 3} // length is defined
  fmt.Println(arr[3])
  // outoput
  0
  
  // or
  
  arr := [...]int{1, 2, 3, 4} // length is referred
  fmt.Println(arr)
  // output
  [1 2 3 4]

• Access array elements

  var arr = [3]int{1, 2, 3}
  fmt.Println(arr[0])
  // output
  1

• initialize specific lements

  arr := [5]int{1:10, 2:20}
  fmt.Println(arr)
  // output
  [0 10 20 0 0]

• Array length

  arr := [5]int{1,2,3,4,5}
  fmt.Println(len(arr))
  // output
  5

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Slices