Session-4.md

We started from the next slide: https://go.dev/tour/basics/15

Topics Covered :

1. Constants

• Constants are declared using const keyword, which can be character, string, boolean or numeric values.
• Constants cannot be declared using the := syntax.
• Constants can be declared with or without a type in Go.

package main

import "fmt"

func main() {
	const message = "You are Learning Go!"
	const time = 07
	const Truth = true
	fmt.Println("Hello,This is Team Shiksha and", message,"which starts at",time ,"?", Truth )
}

• You can also avoid using multiple const keyword and wrap it around brackets.

package main

import "fmt"

func main() {
	const (message = "You are Learning Go!"
		   time = 07
		   Truth = true)
	fmt.Println("Hello,This is Team Shiksha and", message,"which starts at",time ,"?", Truth )
}

• Try Changing the value of 07 to 0700 or 070 and observe the difference in outputs. Can you explain why?

2. Numeric Constants

• Numeric constants are high-precision values. They can be categorized into two types - untyped and typed.

const untypedInteger = 134
const untypedPi = 3.141592

const typedInteger int = 134
const typedPi float64 = 3.141592

• An untyped constant takes the type needed by its context, So When an untyped constant is assigned to a variable, the variable inherits the default type of the constant.

3. For

• Go has only one looping construct, the for loop.
• for loop has three components, each separated by a semicolon ; - init,condition,post.

message := " We are learning for loop"
for i := 0; i < 3; i++ {fmt.Println(i,message)}

• The init and post statements are optional. But parentheses are always required. Check out this For continued

package main

import "fmt"

func main() {
	 i := 1
	
	for ; i < 3; {
		message := " We are learning for loop"
		fmt.Println(i, message) 
		i+=i
	}
}

4. For is Go's "while"

• As init and post statements are optional, for loop can also work as while loop.

5. Forever

• In this, we create an infinite loop.

6. If

• the expression need not be surrounded by parentheses ( ) but the braces { } are required.

package main

import (
	"fmt"
	"math"
)
//To Find Squareroot
func sqrt(x float64) string {
	if x < 0 { //if x is less than 0
		return "\nless than 0"
	}
	return fmt.Sprint("Square root of " , x ," is ", math.Sqrt(x))
}

func main() {
	fmt.Println(sqrt(9), sqrt(-4))
}

7. If with a short statement

• We can also write and declare variables before condition.
• Variables declared by the statement are only in scope until the end of the if.

8. If and else

• Variables declared inside an if short statement are also available inside any of the else blocks.

9. Exercise: Loops and Functions

• We implemented a square root function to find the number z for which z² is most nearly x.

10. Switch

• Go only runs the selected case, not all the cases that follow. Break is implemented automatically.
• It runs the first case whose value is equal to the condition expression.

11. Switch evaluation order

• Switch cases evaluate cases from top to bottom, stopping when a case succeeds.

References

• We Paused on https://go.dev/tour/flowcontrol/10

Optional - Setup Go in your local machine