What are control structures in algorithms and programs?

Also refered to as PROGRAMMING CONSTRUCTS.

Control Structures tell how the instructions you write should be executed or processed.

They determine how the steps in your algorithm or program should flow.

Types of Control Structures

• Sequential

• Selection (conditional)

• Iteration (Repetition / loop)

Control Structures

• Sequential- the instructions are processed (executed) in the order they are written.

• Selection- makes a decision between one or more options.

• Iteration- repeat a set of instructions for a number of times.

Sequential Control Structure Example (Narrative)

1.Ask user to enter 3 numbers

2.Computer accepts numbers

3.Find the sum of the 3 numbers

4.Divide the sum by 3

5.Print Answer

Using Selection/ conditional control structure example (Narrative)

• Ask user to enter 3 numbers

• Computer accepts numbers

• Find the sum of the numbers and store it in the variable total

• If total is greater than 40 then display “very good” ELSE

  Display “too bad”

Iteration/ Repetition Control structure Example (Narrative)

Set X to start at 1; (X = 1)

Repeat the instructions:

1. Ask user to enter 3 numbers

2.Computer accepts numbers

3.Find the sum of the 3 numbers

4.Divide the sum by 3

5.Print Answer

6.Add 1 to X

Until X becomes 20