Go language -- language constants

/*
1.go Language constants
A constant is a simple identifier , When the program is running , The amount that will not be modified
Data types in constants can only be Boolean , Digital （ plastic 、 Floating point and complex Numbers ） And string .
The definition format is
const b type = value
2. According to the omitted type specifier [type], Infer the type of a variable according to its value .
Display type definition ： const b string = “abc”
Implicit type definition ： const b = “abc”
Multiple declarations of the same type can be abbreviated as ：
const a, b = value1 , value2

package main
import “fmt”
func main(){
const Length int = 200
const WIDTH int = 5
var area int
const a,b,c = 1, false, “str”
area = Length * WIDTH
fmt.Printf(“ Area is ：%d”, area)
println()
println(a,b,c)
}
*/

/*
package main
import “unsafe”
const (
a = "ab
b = len(a)
c = unsafe.Sizeof(a)
)
func main(){
println(a,b,c)
}

*/

/*
3.go Language operators
Operators are used to perform data or logical operations while the program is running
go The language's built-in operators are ：
Arithmetic operator （±*% ++ —- /）
Relational operator (== != > < >= <= )
Logical operators (&& And || or ! Not )
An operator （ Operate on the binary bits of integers in memory ）
Assignment operator (= += -= *= /= %= <<= >>= &= ^= |=)
Other operators (& Return variable storage address * Pointer to the variable )

// Arithmetic operator
package main
import “fmt”
func main() {
var a int = 21
var b int = 10
var c int

Log in and copy

c = a + b
fmt.Printf(" first line  - c  The value of is  %d\n", c)
c = a - b
fmt.Printf(" The second line  - c  The value of is  %d\n", c)
c = a * b
fmt.Printf(" The third line  - c  The value of is  %d\n", c )
c = a / b
fmt.Printf(" In the fourth row  - c  The value of is  %d\n", c )
c = a % b
fmt.Printf(" The fifth row  - c  The value of is  %d\n", c )
a++
fmt.Printf(" Sixth elements  - a  The value of is  %d\n", a )
b--
fmt.Printf(" Seventh elements  - b  The value of is  %d\n", b )

}

package main
import “fmt”
func main() {
var a int = 21
var b int = 10
if ( a == b) {
fmt.Printf(“ first line - a be equal to b\n”)
} else {
fmt.Printf(“ first line - a It's not equal to b\n”)
}
if (a < b) {
fmt.Printf(“ The second line - a Less than b \n”)
} else {
fmt.Printf(“ The second line - a Not less than b \n”)
}
if ( a > b) {
fmt.Printf(“ The third line - a Greater than b \n”)
}
a = 5
b = 20
if ( a <= b ) {
fmt.Printf(“ In the fourth row - a Less than or equal to b\n” )
}
if ( b >= a ) {
fmt.Printf(“ The fifth row - b Greater than or equal to a\n” )
}
}

// Logical operators
package main
import “fmt”
func main() {
var a bool = true
var b bool = false
if ( a && b) {
fmt.Printf(“ first line - Condition is true\n”)
}
if ( a || b) {
fmt.Printf(“ The second line - Condition is true\n”)
}
}

// An operator . Bit operators operate on binary bits of integers in memory .& , | ,^
package main
import “fmt”
func main(){
var a uint = 60
var b uint = 13
var c uint = 0
c = a ^ b
fmt.Printf(“ first line -c The value of is %d”,c)
}

// Assignment operator , Simple assignment operators , Assign the value of an expression to an lvalue

A little

// Other operators ,& Return variable storage address ,&a The actual address of the variable will be given ,* Pointer to the variable ,*a Is a pointer variable .
package main
import “fmt”
func main() {
var a int = 4
var b int32
var c float32
var ptr *int
fmt.Printf(“ first line - a The variable type is = %T\n”, a )
fmt.Printf(“ The second line - b The variable type is = %T\n”, b )
fmt.Printf(“ The third line - c The variable type is = %T\n”, c )

Log in and copy

ptr= &a
fmt.Printf("a  The value of is  %d\n",a )
fmt.Printf("*ptr  by  %d\n", *ptr )

}
*/

// Operator precedence . Operators have precedence , The operation direction of binary operators is from left to right ,*/<< >> & &^ > =-|^ > == != < > > && > || You can use parentheses to raise the overall operator priority of an expression
package main
import “fmt”
func main() {
var a int = 20
var b int = 10
var c int = 15
var d int = 5
var e int ;
e = (a+b) * c /d;
fmt.Printf(“(a + b) * c / d The value of is : %d\n”, e );
e = ((a + b) * c) / d; // (30 * 15 ) / 5
fmt.Printf(“((a + b) * c) / d The value of is : %d\n” , e );

e = (a + b) * (c / d); // (30) * (15/5)
fmt.Printf(“(a + b) * (c / d) The value of is : %d\n”, e );

e = a + (b * c) / d; // 20 + (150/5)
fmt.Printf(“a + (b * c) / d The value of is : %d\n” , e );
}