PYTHON:Count Prime Numbers in List

Count how many prime numbers are present in a list of integers.

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Python Program Code

This program helps you to learn the fundamental structure and syntax of Python programming.

Try This Code
count-prime-numbers-in-list.py
# Program to count prime numbers in a list

def is_prime(n: int) -> bool:
    if n < 2:
        return False
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return True

numbers = list(map(int, input("Enter integers separated by space: ").split()))

count = sum(1 for x in numbers if is_prime(x))

print("Number of primes in list:", count)
Terminal Output
Enter integers separated by space: 2 3 4 5 6
Number of primes in list: 3

Understanding Count Prime Numbers in List

We define a helper is_prime and count how many list elements satisfy it.

Note: To write and run Python programs, you need to set up the local environment on your computer. Refer to the complete article Setting up Python Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your Python programs.

Practical Learning Notes for Count Prime Numbers in List

This Python program is part of the "List Programs" topic and is designed to help you build real problem-solving confidence, not just memorize syntax. Start by understanding the goal of the program in plain language, then trace the logic line by line with a custom input of your own. Once you can predict the output before running the code, your understanding becomes much stronger.

A reliable practice pattern is to run the original version first, then modify only one condition or variable at a time. Observe how that single change affects control flow and output. This deliberate style helps you understand loops, conditions, and data movement much faster than copying full solutions repeatedly.

For interview preparation, explain this solution in three layers: the high-level approach, the step-by-step execution, and the time-space tradeoff. If you can teach these three layers clearly, you are ready to solve close variations of this problem under time pressure.

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