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What are different types of control structures? Define each.

Published in Programming Concepts 4 mins read

Control structures are the building blocks of programming logic, dictating the order in which instructions are executed. They allow you to control the flow of your program, making it more efficient and flexible. Here are the most common types:

1. Sequential Control

The most basic control structure, sequential control executes statements in the order they appear in the code. This is the default flow of execution in most programming languages.

Example:

print("Hello")
print("World")

This code will print "Hello" followed by "World" on separate lines.

2. Selection Control

Selection control structures, also known as conditional statements, allow you to choose which block of code to execute based on a condition. The most common selection structures are:

a. if-else Statements:

  • Execute a block of code if a condition is true and another block if it's false.
age = 18
if age >= 18:
  print("You are an adult.")
else:
  print("You are not an adult.")

b. if-elif-else Statements:

  • Provide multiple conditions to check, executing the corresponding block of code if the condition is true.
grade = 85
if grade >= 90:
  print("A")
elif grade >= 80:
  print("B")
else:
  print("C")

c. Switch Statements (or Case Statements):

  • Compare a value with multiple cases and execute the corresponding code block.
day = "Monday"
switch (day) {
  case "Monday":
    print("Start of the week.")
    break;
  case "Friday":
    print("End of the week.")
    break;
  default:
    print("Another day.")
}

3. Iteration Control

Iteration control structures, also known as loops, allow you to repeat a block of code multiple times. The most common iteration structures are:

a. For Loops:

  • Execute a block of code a fixed number of times.
for i in range(5):
  print(i)

This code will print numbers from 0 to 4.

b. While Loops:

  • Execute a block of code as long as a condition is true.
count = 0
while count < 5:
  print(count)
  count += 1

This code will print numbers from 0 to 4.

c. Do-While Loops:

  • Execute a block of code at least once, and then continue as long as a condition is true.
count = 0
do {
  print(count)
  count += 1
} while (count < 5);

This code will print numbers from 0 to 4.

4. Jump Statements

Jump statements allow you to alter the normal flow of execution within a program. Common jump statements include:

a. break:

  • Immediately exits the innermost loop.
for i in range(10):
  if i == 5:
    break
  print(i)

This code will print numbers from 0 to 4, as the loop breaks when i reaches 5.

b. continue:

  • Skips the current iteration of the loop and proceeds to the next iteration.
for i in range(10):
  if i == 5:
    continue
  print(i)

This code will print numbers from 0 to 9, except for 5.

c. return:

  • Exits a function and returns a value.
def add(x, y):
  return x + y

This function adds two numbers and returns their sum.

d. goto:

  • Transfers control to a specific labeled statement in the program. This statement is generally discouraged in modern programming practices due to its potential to create complex and hard-to-understand code.

Conclusion

Control structures are essential for creating dynamic and efficient programs. By understanding and applying these structures, you can create code that performs complex tasks, handles different scenarios, and executes instructions in a controlled manner.

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