Master Go Operators: From Arithmetic to Pointers with Practical Examples

1 Operator Classification

1 算数运算符：+,-,*,/,%,++,--
2 赋值运算符：=,+=,-=,*=,/=,%=
3 关系运算符：==,!=,<,>,<=,>=
4 逻辑运算符：&&,||,!
5 位运算符：&,|,^,<<,>>
6 其他运算符：&,*

2 Arithmetic Operators

2.1 "+" Example

package main

import "fmt"

func main() {
    // "+" can denote a positive number
    var x = +4
    fmt.Println(x)
    // "+" can perform addition
    var y = 3 + 4
    fmt.Println(y)
    // string concatenation using "+"
    var str1 = "hello" + " word!"
    fmt.Println(str1)
}

4
7
hello word!

2.2 "/" Example

package main

import "fmt"

func main() {
    // Integer division yields an integer result
    var x = 10 / 3
    fmt.Println(x)
    // Floating‑point division yields a float result
    var y = 10.00 / 3
    fmt.Println(y)
}

3
3.3333333333333335

2.3 "%" Example

package main

import "fmt"

func main() {
    // Modulo operation works with integers
    var x = 15 % 6
    fmt.Println(x)
    fmt.Println(-15 % 6)
    fmt.Println(-15 % -6)
    fmt.Println(15 % -6)
}

3
-3
-3
3

2.4 "++" Example

package main

import "fmt"

func main() {
    // ++ increments, -- decrements; must appear after the variable
    var a int = 5
    a++
    fmt.Println(a)
    a--
    fmt.Println(a)
}

6
5

3 Assignment Operators

3.1 "+=" and "/=" Example

package main

import "fmt"

func main() {
    var a int = 5
    a += 3 // equivalent to a = a + 3
    fmt.Println(a)
    a /= 4 // equivalent to a = a / 4
    fmt.Println(a)
}

8
2

4 Relational Operators

Relational operators always return a bool value (true or false).

They are commonly used in control‑flow statements.

4.1 Example

package main

import "fmt"

func main() {
    var a int = 5
    b := 6
    fmt.Println("a =", a, "; b =", b)
    fmt.Println("a > b", a > b)
    fmt.Println("a < b", a < b)
    fmt.Println("a == b", a == b)
    fmt.Println("a != b", a != b)
    fmt.Println("a <= b", a <= b)
    fmt.Println("a >= b", a >= b)
}

a = 5 ; b = 6
false
true
false
true
true
false

5 Logical Operators

5.1 Example

package main

import "fmt"

func main() {
    fmt.Println(true && false)
    fmt.Println(true || false)
    fmt.Println(true && true)
    fmt.Println(!true)
}

false
true
true
false

6 Bitwise Operators

Bitwise operators work on the binary representation of integer values. They are fast and often used in low‑level programming.

6.1 Logical Bitwise Operators

&  — both bits are 1 → result 1 (AND)
|  — at least one bit is 1 → result 1 (OR)
^  — bits differ → result 1 (XOR)

6.2 Shift Operators

<< shifts bits left, filling with 0s; >> shifts bits right, preserving the sign for signed integers.

package main

import "fmt"

func main() {
    var a int8 = +85
    var b int8 = -43
    fmt.Println(a << 3)
    fmt.Println(a >> 3)
    fmt.Println(b >> 3)
}

-88
10
-6

7 Pointers – Derived Types

7.1 Basic Introduction

1. A variable represents a memory region with a name, type, and value.
2. A pointer variable stores the address of another variable.
3. Declaration example: var ptr *int = &someVariable

8 Other Operators (& and *)

1. & returns the address of a variable.
2. * dereferences a pointer to obtain the value stored at that address.

8.1 Example

8.1.1 Viewing Address and Value

package main

import "fmt"

func main() {
    var a int = 8
    var ptr *int = &a
    fmt.Println("Address of a:", ptr)
    fmt.Println("Value at ptr:", *ptr)
}

Address of a: 0xc000012088
Value at ptr: 8

8.1.2 Modifying a Variable via Pointer

package main

import "fmt"

func main() {
    var a int = 9
    fmt.Printf("a address= %v
", &a)
    var ptr *int
    ptr = &a
    *ptr = 10
    fmt.Println(a)
    fmt.Printf("a address= %v
", &a)
}

a address= 0xc000012088
10
a address= 0xc000012088