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Lesson 6Controlling Program Flow with Loops

As you learned in the previous lesson, without specific  instructions, a program executes statements linearly until the program ends or until an error causes the program to fail. You also saw how to change the flow of your programs based on conditions.

In this lesson, you will learn how to repeat a line of code or set of instructions. We will look at the use of looping to control the flow of a program during runtime as well as cover a few related items for adjusting the flow of a program from within a loop.

LEARNING OBJECTIVES

By the end of this lesson, you will be able to:

• Learn how to repeat sections of code.
• Explore the for keyword.
• Understand how to stop or exit a loop.
• Discover how to loop through a string.
• Explore the concept of a never-ending infinite loop.

LOOPING STATEMENTS

In every programming language, it is important to be able to repeat statements without having to write the statements over and over. For example, Listing 6.1 uses only what you've learned so far to print the values 1 to 10 using a single variable.

LISTING 6.1Counting to 10 linearly

package main
 
import "fmt"
 
func main() {
   var ctr int = 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
   ctr += 1
   fmt.Println(ctr)
}

When you run this listing, ...