Python Program - Count the Occurrence of an Item in a List

Here's a Python program that counts the occurrence of an item in a list:

def count_occurrences(lst, item):
    count = 0
    for i in lst:
        if i == item:
            count += 1
    return count

# Example usage
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 2, 2, 3, 3, 3]
print(count_occurrences(my_list, 3))  # Output: 4

In this program, the count_occurrences() function takes two arguments - lst (the list to be searched) and item (the item whose occurrence needs to be counted).

The function initializes a counter variable count to 0, and then loops through each element of the list lst. If an element in the list matches the item, then the count variable is incremented by 1.

After the loop finishes, the function returns the final value of count, which represents the number of times the item appears in the lst.

In the example usage, we define a list my_list and call the count_occurrences() function with arguments my_list and 3. The program outputs the number of times 3 appears in my_list, which is 4.