The for range construct is useful in many context. It can be used to traverse every item in a collection. It is similar to foreach in other languages. But, we still have the index at each iteration in for range construct.
Syntax:
Go For Range Example
Output:
sum: 60 1 -> mango 2 -> apple 3 -> banana key: 1 key: 2 key: 3 0 72 1 105
The for loop loops through a block of code a specified number of times.
The for loop is the only loop available in Go.
Loops are handy if you want to run the same code over and over again, each time with a different value.
Each execution of a loop is called an iteration.
The for loop can take up to three statements:
for statement1; statement2; statement3 {
// code to be executed for each iteration
}statement1 Initializes the loop counter value.
statement2 Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
statement3 Increases the loop counter value.
Note: These statements don't need to be present as loops arguments. However, they need to be present in the code in some form.
This example will print the numbers from 0 to 4:
package main
import ("fmt")
func main() {
for i:=0; i < 5; i++ {
fmt.Println(i)
}
}Result:
0
1
2
3
4
This example counts to 100 by tens:
package main
import ("fmt")
func main() {
for i:=0; i <= 100; i+=10 {
fmt.Println(i)
}
}Result:
0
10
20
30
40
50
60
70
80
90
100
The continue statement is used to skip one or more iterations in the loop. It then continues with the next iteration in the loop.
This example skips the value of 3:
package main
import ("fmt")
func main() {
& for i:=0; i < 5; i++ {
if i == 3 {
continue
}
fmt.Println(i)
}
}
Result:
0
1
2
4
The break statement is used to break/terminate the loop execution.
This example breaks out of the loop when i is equal to 3:
package main
import ("fmt")
func main() {
for i:=0; i < 5; i++ {
if i == 3 {
break
}
fmt.Println(i)
}
}
Result:
0
1
2
Note: continue and break are usually used with conditions.
It is possible to place a loop inside another loop.
Here, the "inner loop" will be executed one time for each iteration of the "outer loop":
package main
import ("fmt")
func main() {
adj := [2]string{"big", "tasty"}
fruits := [3]string{"apple", "orange", "banana"}
for i:=0; i < len(adj); i++ {
for j:=0; j < len(fruits); j++ {
fmt.Println(adj[i],fruits[j])
}
}
}Result:
big apple
big orange
big banana
tasty apple
tasty orange
tasty banana
The range keyword is used to more easily iterate over an array, slice or map. It returns both the index and the value.
The range keyword is used like this:
for index, value := array|slice|map {
// code to be executed for each iteration
}This example uses range to iterate over an array and print both the indexes and the values at each (idx stores the index, val stores the value):
package main
import ("fmt")
func main() {
fruits := [3]string{"apple", "orange", "banana"}
for idx, val := range fruits {
fmt.Printf("%v\t%v\n", idx, val)
}
}Result:
0 apple
1 orange
2 banana
Tip: To only show the value or the index, you can omit the other output using an underscore (_).
Here, we want to omit the indexes (idx stores the index, val stores the value):
package main
import ("fmt")
func main() {
fruits := [3]string{"apple", "orange", "banana"}
for _, val := range fruits {
fmt.Printf("%v\n", val)
}
}Result:
apple
orange
banana
Here, we want to omit the values (idx stores the index, val stores the value):
package main
import ("fmt")
func main() {
fruits := [3]string{"apple", "orange", "banana"}
for idx, _ := range fruits {
fmt.Printf("%v\n", idx)
}
}Result:
0
1
2The Go switch statement executes one statement from multiple conditions. It is similar to if-else-if chain statement.
Syntax:
The switch statement in Go is more flexible. In the above syntax, var1 is a variable which can be of any type, and val1, val2, ... are possible values of var1.
In switch statement, more than one values can be tested in a case, the values are presented in a comma separated list
like: case val1, val2, val3:
If any case is matched, the corresponding case statement is executed. Here, the break keyword is implicit. So automatic fall-through is not the default behavior in Go switch statement.
For fall-through in Go switch statement, use the keyword "fallthrough" at the end of the branch.
Go Switch Example:
Output:
Enter Number: 20 the value is 20
or
Output:
Enter Number: 35 It is not 10,20,30,40
Go switch fallthrough example
Output:
was <= 30 was <= 40 was <= 50 was <= 60 default case
The if statement in Go is used to test the condition. If it evaluates to true, the body of the statement is executed. If it evaluates to false, if block is skipped.
Syntax :
Go if example
Output:
a is even number
The if-else is used to test the condition. If condition is true, if block is executed otherwise else block is executed.
Syntax :
Go if-else example
Output:
a is even value of a is : 10
Go If-else example: with input from user
Output:
Enter number: 10 10 is even
The Go if else-if chain is used to execute one statement from multiple conditions.
We can have N numbers of if-else statement. It has no limit.
The curly braces{ } are mandatory in if-else statement even if you have one statement in it. The else-if and else keyword must be on the same line after the closing curly brace }.
Go If else-if chain Example
Output:
Enter text: 84 A Grade
We can also nest the if-else statement to execute one statement from multiple conditions.
Syntax
nested if-else example
Output:
Inside nested If Statement Value of x is : 10 Value of y is : 20