Question

Respond to the following in a minimum of 175 words:

The flow of a program is controlled by different structures. The three basic control structures in computer programs are sequence structures, decision structures (also called selection structures), and repetition structures (also called iteration structures).

Discuss the differences between decision structures and repetition structures used in algorithms. Provide examples of when you might use each.

Answer 1

The three basic control structures for any program are :

• Sequence Structure: Sequence structure is like following a recipe where one step is followed after another step by step. In this, the instructions execute in the same order as they are written in the script.
• Selection Structure: In this structure, the code executes based on the decision made by the currently executing line of code. Depending on whether the condition is true or false, the code skips to the next block for further execution. Example: if-else block, switch condition, etc.
• Repetition / Iteration Structure: In case of iteration the same statement of code is executed multiple times as specified until the condition has been met. It includes for loops, while loops etc.

The difference between decision structure and Repetition structure used in algorithms:

1. Decision Structure: These statements make evaluations based on the comparator operators used in the statements lile ' = ' , '>' , '<' ,'>=' , '<=' , '==' etc. It can also contain boolean operators like OR operator, AND operator and the overall output of the expression determines the output. The precedence rule of operators must always be taken into consideration for the evaluation of these expressions.

• If-Else Algorithm

if (Condition set according to the user )

{

//block of code for execution

}

else if (Another condition set according to the user)

{

//block of code for execution

}

else

{

// the block of code that executes when the above conditions are not satisfied

}

• Switch Algorithm

Switch (the value that will act as switching parameter) :

{

case 1 : // block of code for execution

break;

case 2 : // block of code for execution

break;

break://Default block of code that executes if none of the conditions match

}

2. Repetition Structure

• For Loop Algorithm

for(initialization, condition for looping, increment)

{

//Block of code for execution.

}

Example: for(int i=0;i<5;i++)

{

System.out.println("Hello World ");

}

• While Loop Algorithm

initialization

while(condition that needs to be satisfied for execution)

{

//block of code for execution

( increment or decrement operator if required)

}

• Do-While Loop Algorithm (Advantage : Executes minimum one time)

do

{

// block of code for execution

} while( condition )