Control Statements in Python

Last Updated on April 20, 2023 by Prepbytes

Loops, as you may know, are used in Python to iterate over a block of code repeatedly. However, you may want to shift control once a specific condition is met. This is where control statements in Python come into play. In this article, we will discuss control statements in Python, the types of control statements in Python, and the uses of control statements in Python.

What are Control Statements in Python?

Control statements are an essential aspect of any programming language, including Python. Control statements in Python are used to manage the flow of execution of a program based on certain conditions.

Control statements in Python are a powerful tool for managing the flow of execution. They allow developers to make decisions based on specific conditions and modify the normal sequential flow of a program. By using control statements effectively, developers can write more efficient and effective code.

Types of Control Statements in Python

There are three types of control statements in Python.

Break Statement in Python

The break statement is used to terminate a loop, i.e., for loop, while loop, or nested loop. When a break statement executes inside a loop, it immediately terminates the loop and transfers control to the statement following the loop.

Flow Chart of Break Statement in Python

Syntax of Break Statement in Python

The syntax of break statement in Python is as follows:

while condition:
    # statements
    if condition:
        break
    # statements after break statement

In this syntax, the break statement is used inside a loop (while loop or for loop). When the condition specified in the if statement is true, the break statement is executed, and the control is transferred to the next statement after the loop. This means that the loop is terminated, and the code execution continues from the statement after the loop.

Example of Break Statement in Python

Here’s an example of the break statement in Python:

list_of_numbers = [1, 3, 7, 9, 11, 12, 13, 15]

for num in list_of_numbers:
    if num % 2 == 0:
        print("The first even number is:", num)
        break

Output:

The first even number is: 12

Explanation:
In this example, we have a list called list_of_numbers. We want to find the first even number in this list. We use a for loop to iterate over the list, and inside the loop, we use an if statement to check if the current number is even. If the current number is even, we print it as the first even number, and we use the break statement to exit the loop.

Continue Statement in Python

The continue statement is used to skip a particular iteration of a loop when a specific condition is met. When a continue statement is executed inside a loop, it skips the current iteration of the loop and jumps to the next iteration.

Flow chart of Continue Statement in Python

Syntax of Continue Statement in Python

The syntax for the continue statement in Python is as follows:

while condition:
    # statements before the continue statement
    if condition:
        continue
    # statements after the continue statement

In this syntax, when the condition specified in the if statement is true, the continue statement is executed, and the control is transferred to the next iteration of the loop. This means that the current iteration is skipped, and the loop continues with the next iteration.

Example of Continue Statement in Python

Here’s an example of the continue statement in Python:

numbers = [1, 3, 7, 8, 9, 11, 12, 15]

for num in numbers:
    if num % 2 == 0:
        continue
    print(num)

Output:

1
3
7
9
11
15

Explanation: We have a list of integers called numbers. Only the odd numbers from this list should be printed. We use a for loop to traverse through the list, and an if statement inside the loop checks if the current number is even. If the current number is an even integer, we apply the continue statement to skip the current iteration and proceed to the next. We print the current number if it is odd.

Pass Statement in Python

The pass statement is a placeholder statement that does nothing. It is used when a statement is required syntactically, but you don’t want to execute any code. Pass is mostly used as a placeholder for functions or conditional statements that have not yet been implemented.

Syntax of Pass Statement in Python

The syntax for the pass statement in Python is as follows:

while condition:
    # statements before the pass statement
    if condition:
        pass
    # statements after the pass statement

In this syntax, the pass statement is used inside a loop (while loop or for loop) and inside an if statement. When the pass statement is executed, it does nothing, and the control is transferred to the next statement after the loop or the if statement.

Example of Pass Statement in Python

Here’s an example of the pass statement in Python:

x = 25

if x > 15:
    pass
else:
    print("x is less than or equal to 15")

Explanation: In this example, we have a variable called x that has a value of 10. We want to print a message when the value of x is greater than 5. We use an if statement to check if the value of x is greater than 5. Inside the if statement, we use the pass statement as a placeholder for the code that we haven’t written yet. If the value of x is less than or equal to 5, we print a message.

When we run this program, it will not output anything, as the pass statement does nothing. However, it serves as a placeholder for the code that we will write in the future.

Uses of Control Statements in Python

Here are some of the common uses of control statements in Python:

1. Conditionally executing code: The if-else statement is used to execute specific code based on a condition. This allows us to selectively execute certain parts of the code based on the input data or the state of the program.
2. Repeating code: Loops such as for loop and while loop are used to execute a block of code repeatedly based on a condition. This is useful when we want to perform a specific operation multiple times, such as processing a list of items or iterating over a range of numbers.
3. Exiting loops: The break statement is used to exit a loop prematurely when a specific condition is met. This is useful when we want to terminate a loop when we have found the desired value or have encountered an error condition.
4. Skipping iterations: The continue statement is used to skip a specific iteration of a loop when a particular condition is met. This is useful when we want to exclude specific values from the loop, such as even numbers or duplicates.
5. Handling errors: The try-except statement is used to handle errors that may occur during the execution of a program. This allows us to gracefully handle errors and prevent the program from crashing.

Conclusion
In conclusion, control statements in Python are used to control the flow of execution of a program. The three types of control statements are break, continue, and pass. These statements allow us to selectively execute specific parts of the code based on certain conditions, optimize performance, and handle errors. By using control statements in Python effectively, we can write more efficient and error-free code.

FAQs on Control Statements in Python

Here are some frequently asked questions on control statements in Python.

Q1: What is the difference between a break statement and a continue statement in Python?
Ans: The break statement is used to exit a loop prematurely when a specific condition is met, whereas the continue statement is used to skip a specific iteration of a loop when a particular condition is met.

Q2: Can we use a break statement outside of a loop in Python?
Ans: No, we cannot use a break statement outside of a loop in Python.

Q3: Can we use a pass statement outside of a loop or an if statement in Python?
Ans: Yes, we can use a pass statement outside of a loop or an if statement in Python. However, it will not have any effect on the program’s execution.

Q4: What is the use of the break statement in a nested loop in Python?
Ans: The break statement in a nested loop is used to exit out of both loops when a specific condition is met.

Q5: What is the use of the continue statement in a nested loop in Python?
Ans: The continue statement in a nested loop is used to skip a specific iteration of the inner loop when a particular condition is met, without exiting out of the outer loop.