The purpose of a control structure is to change the sequence of control in a program. In the absence of a control structure, the program flows in a linear way, executing line by line. The presence of a control structure changes the program flow by choosing the right path based on a decision. The common control structures can be characterised as follows:

1. Decision Control Structures

2. Loop Control Structures

3. Case Control Structure

4. Jumping Control Structure

Decision Control Structures

We can have different forms of decision control structures as follows:

• if

• if..else

• if..else if..else

• nested if