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Numeric Types:
-
int: Signed integer type. -
int8, int16, int32, int64: Signed integer types with specific bit sizes. -
uint: Unsigned integer type. -
uint8, uint16, uint32, uint64: Unsigned integer types with specific bit sizes. -
float32, float64: Floating-point types for representing decimal numbers. -
complex64, complex128: Complex number types for representing real and imaginary parts.
Positive and negative integer
intdepends on the running system. If you're running Go on 32-bit OS system, the default type forintisint32， and its range is -2^31 to 2^31-1(-2147483648, 2147483647)
Positive integer
unit8has the range of(0, 2^8-1), i.e.(0, 255)
Boolean Type:
bool: Represents a Boolean value (true or false).
String Type:
string: Represents a sequence of characters.
Array Types:
array: A fixed-size collection of elements of the same type. The size of an array is determined at compile-time.
Slice Type:
slice: A flexible, dynamically-sized sequence of elements. Slices are built on top of arrays.
package main
import (
"fmt"
)
func main() {
var intA int = -12
fmt.Printf("\nintA: %d", intA)
//intA: -12
var intB uint = 12
fmt.Printf("\nintB: %d", intB)
//intB: 12
var floatA float64 = 98.6
fmt.Printf("\nfloatA: %f", floatA)
//floatA: 98.600000
var stringVar string = "hello world!"
fmt.Printf("\nstringVar: %s", stringVar)
// stringVar: hello world!
var boolVar bool = true
fmt.Printf("\nboolVar: %t\n", boolVar)
// boolVar: true
var numbers = []int{0, 1, 2, 3, 4, 5}
fmt.Printf("Size of 'numbers' is %d\n", len(numbers))
fmt.Println(numbers)
// Size of 'numbers' is 6
// [0 1 2 3 4 5]
numbers = append(numbers, 6, 7)
fmt.Printf("Size of 'numbers' is changed to %d\n", len(numbers))
fmt.Println(numbers)
// Size of 'numbers' is changed to 8
// [0 1 2 3 4 5 6 7]
sliced := numbers[1:5]
fmt.Printf("sliced numbers: ")
fmt.Println(sliced)
// sliced numbers: [1 2 3 4]
numberArray := [3]int{1, 2}
fmt.Printf("numberArray with size 3 and default value:")
fmt.Println(numberArray)
// numberArray with size 3 and default value:[1 2 0]
}
Map Type:
map: An unordered collection of key-value pairs, where each key is unique.
package main
import "fmt"
func main() {
// Create a map to store employee names and their corresponding IDs
// key: string, value: int
employees := make(map[string]int)
fmt.Printf("current size of this map: %d\n", len(employees))
// current size of this map: 0
// Add key-value pairs to the map
employees["John"] = 1001
employees["Alice"] = 1002
employees["Bob"] = 1003
fmt.Println(employees)
// map[Alice:1002 Bob:1003 John:1001]
// Accessing values from the map
fmt.Println(employees["Alice"])
// Output: 1002
// Modifying values in the map
employees["Bob"] = 1004
// Deleting a key-value pair from the map
delete(employees, "John")
// Print the updated map
fmt.Println(employees)
// map[Alice:1002 Bob:1004]
// Checking if a key exists in the map
id, exists := employees["Alice"]
if exists {
fmt.Println("Alice's ID:", id)
// Alice's ID: 1002
} else {
fmt.Println("Alice not found")
}
var keys []string
for key :=range employees {
keys = append(keys, key)
}
fmt.Printf("Keys from the map 'employees': ")
fmt.Println(keys)
// Keys from the map 'employees': [Alice Bob]
}
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