Discuss the three types of control structures. Describe how any one of these control structures impacts your program flow. Do any of these structures have to follow a specific order?
The three types of control structures in programming are sequence, selection, and repetition (also known as iteration).
1. Sequence: In a sequence control structure, the instructions are executed one after another in a predefined order. This type of control structure is common in most programming languages. It ensures that the program executes instructions in the specified sequence, allowing for logical and organized flow.
For example, consider a program that calculates the sum of two numbers. In a sequence structure, the program would read the first number input, read the second number input, add them together, and then display the result.
2. Selection: The selection control structure allows the program to make decisions based on certain conditions. It involves the use of if-else statements or switch-case statements. These statements evaluate a condition and execute different sets of instructions based on the condition's result.
Suppose you have a program that determines whether a given number is even or odd. In a selection structure, the program would check if the number is divisible by 2 (using the modulus operator). If the result is 0, it indicates an even number, and the program can display that information. Otherwise, it can display that the number is odd. The selection structure impacts the program flow by executing different sets of instructions depending on the condition.
3. Repetition: Repetition control structures allow the program to loop through a set of instructions multiple times until a certain condition is met. This type of structure is useful in situations where you need to repeat a certain task a specific number of times or until a condition becomes false.
For instance, imagine a program that asks the user to enter five numbers and then calculates their sum. In a repetition structure like a for loop, the program can prompt the user for input five times and store each value in a variable. After all the inputs are collected, the program can then calculate and display the sum of those numbers. The repetition structure impacts the program flow by repeatedly executing a set of instructions until the condition is met.
The three control structures don't necessarily have to follow a specific order. However, the order in which they appear in a program can affect its logic and outcome. Sequence structures provide the foundation for the program, ensuring a predefined order of execution. Selection structures are often used within sequence structures to make decisions at specific points. Repetition structures can be used within both sequence and selection structures, allowing certain instructions or conditions to be repeated multiple times.