Go lang Basic

#programming #go #webdev #javascript

Data type in Go lang

int
int8
int16
int32
int64

uint

uint
uint8
uint16
uint32
uint64

float

float32
float64

string
slice
array
map
struct
Interface{} 10.Pointer 11.you can assign only a positive value in an unsigned integer

The default value of Data Type

The default value of int is 0.
The default value of float is 0.0.
The default value of a string is “”.
The default value of a slice is nil.
The default value of the array depends on the assigned data type.
The default value of a map is nil.
The default value of a struct is nil.
The default value of an interface is nil.
The default value of a pointer is nil.

Explanation of Data Types

Slice

slice does not define the number of items
The default value of a slice is nil.
Slice has capacity & length.
We can append the slice data.
we can access the slice like an array.
we can assign unlimited data in a slice

package main
import "fmt"
func main() {
    a := []int{1,3,4,5}
    res := sum(a)
    fmt.Println("slice: ", res)
    res = multi(a)
    fmt.Println("slice: ", res)
}

func sum(number []int) int {
    total := 0
    for _, num:= range number {
        total += num
    }
    return total
}
func multi(number []int) int {
    total := 1
    for _, num:= range number {
        total *= num
    }
    return total
}

Array

The number of data is defined in an array.
The default value of the array depends on the assigned data type.
The array has only length and doesn't have capacity.
We can't append an array, we can index an array
The size of the array is also called, more data cannot be assigned.
We can index keys and values in an array.
If we have to check the length of the array, we can use the default built-in function len() and print the required data in the terminal or web.

package main
import "fmt"
func main() {
    a := [5]int{}
    fmt.Println("integer Array: ", a)

    var b = [4]string{
        "codemen",
        "m",
        "codemen",
        "codemen",
    }
    fmt.Println("Name: ", b)

    colors := [4]string{
        "roje","gris","azul","black"}

        fmt.Println("Name: ", colors)
}

Map

The default key of a map could be an integer or a string. The value could be any type of data like integer, string, slice, array, or map.

package main

import "fmt"

type Vertex struct {
    Lat, Long float64
}

var m map[string]Vertex
func main() {
    m = make(map[string]Vertex)
    m["Bell Labs"] = Vertex{
        40.68433, -74.39967,
    }
    fmt.Println(m["Bell Labs"])
}

var a string = "codemen"
var m map[string]string
func main() {
    m = make(map[string]string)
    m["Hello String"] = a
    fmt.Println(m["Hello String"])
}

Struct

Struct users define data type.

Interface

An interface can use for dynamic purposes. We can assign any kind of data in an interface.
We can declare/signature a method in an interface. We can't implement it in an interface.
In an interface, we can define methods type, arguments, and return type.

Pointer

A pointer holds the address of a variable
A pointer holds its memory address of Ram.
To dynamically change the variable value we can use a pointer
If we want to change one of the variable's values under the block, function, for loop, if conditions, then we can use a pointer to hold the variable's value and change it through it.