{"id":7216,"date":"2023-01-21T19:42:48","date_gmt":"2023-01-21T14:12:48","guid":{"rendered":"https:\/\/tutorpython.com\/?p=7216"},"modified":"2023-10-19T15:08:35","modified_gmt":"2023-10-19T09:38:35","slug":"for-loops-in-python","status":"publish","type":"post","link":"https:\/\/tutorpython.com\/for-loops-in-python","title":{"rendered":"For Loops in Python"},"content":{"rendered":"

In this article, we will learn about the different types of for loops in Python<\/a> and how to use them effectively in our code. The loop is a fundamental concept in Python programming. And implementation of for loop<\/strong> is particularly powerful and versatile.<\/p>\n

We will start with the basic standard “for” loop which includes how to iterate over a sequence and use the range function. Next, we will see how the “for-each” loop differs from the standard for loop.<\/p>\n

Types of For loop in Python<\/h2>\n

There are two main types of for loops in Python:<\/p>\n

    \n
  1. The standard for loop<\/strong>\u00a0iterates over a sequence of items (such as a list or string) and assigns each item to a variable on each iteration.<\/li>\n
  2. And “for-each<\/strong>” loop, is implemented using the for<\/strong> keyword along with the in<\/strong> the keyword. This type of loop iterates over the elements of an iterable object (such as a list or dictionary), rather than using an index.<\/li>\n<\/ol>\n

    How can I write for loop in Python?<\/h2>\n

    Below is the syntax<\/a> for loop in Python with code examples and explanations.<\/p>\n

    Syntax of For loop in Python<\/h3>\n

    The syntax for a standard for loop in Python<\/a> is as follows:<\/p>\n

    for variable in sequence:\r\n    # code to execute on each iteration\r\n<\/code><\/pre>\n
    Here, the for <\/strong>in Python keyword<\/a> is used to initiate the loop. The variable<\/strong> is a placeholder that takes on the value of the next item in the sequence<\/strong> on each iteration. The sequence<\/strong> is the list, tuple, string, etc. that we want to iterate over. The code indented under the for<\/strong> statement is executed on each iteration.<\/p>\n
    Example:<\/p>\n
    numbers = [1, 2, 3, 4, 5]\r\nfor num in numbers:\r\n    print(num)\r\n<\/code><\/pre>\n
    The output for this code will be:<\/p>\n
    1\r\n2\r\n3\r\n4\r\n5<\/pre>\n
    Here, the for loop helps us to print out the contents of the numbers<\/strong> list through each iteration.<\/p>\n
    It is important to note that the for loop must be indented properly, otherwise, we will get an IndentationError<\/strong>.<\/p>\n
    Python For Loop using Python range()<\/h2>\n
    One common use of for loops in Python<\/strong> is to iterate over a range of numbers using the range()<\/strong> function. The range()<\/strong> function generates a sequence of numbers within a specified range.<\/p>\n
    The basic syntax for using the range() function is as follows:<\/p>\n
    range(start, stop, step)\r\n<\/code><\/pre>\n
    Here, the start<\/strong> is the first number in the range (default is 0). The stop<\/strong> is the last number in the range (this number is not included in the range). The step<\/strong> is the difference between each number in the range (default is 1).<\/p>\n
    Example of Python for and range function-<\/p>\n
    for i in range(2, 10, 2):\r\n    print(i)\r\n<\/code><\/pre>\n
    The output for this code will be:<\/p>\n
    2\r\n4\r\n6\r\n8<\/pre>\n
    Here, we see that using the range()<\/strong> function in a for loop in Python we are able to print out the numbers between 2 and 10(excluded) with a difference of 2 digits.<\/p>\n
    It’s important to note that when using range()<\/strong> in a for loop, the loop variable (i.e., i<\/strong> in the above example) will take on the value of the next number in the range on each iteration, rather than the next item in a list or other iterable object.<\/p>\n
    The range()<\/strong> function is very useful for performing a specific number of iterations or for generating a sequence of numbers for use in mathematical operations or other calculations. Moreover, the range() function can also be converted to a list<\/a>, tuple<\/a>, or set<\/a> with the use of list()<\/strong>, tuple(),<\/strong> or set()<\/strong>.<\/p>\n
    For loop in Python with index<\/h2>\n
    Sometimes it is useful to know the index of the current item in a loop.<\/p>\n
    Python provides the built-in function enumerate()<\/code> which can be used in combination with the for loop to get the index of the current item.<\/p>\n
    The syntax of For loop is as follows-<\/p>\n
    for index, variable in enumerate(sequence):\r\n    # code to execute for each iteration\r\n<\/code><\/pre>\n
    Example of For loop in Python with index-<\/p>\n
    fruits = [\"apple\", \"banana\", \"cherry\"]\r\nfor index, fruit in enumerate(fruits):\r\n    print(index, fruit)\r\n<\/code><\/pre>\n
    The output of this will be:<\/p>\n
    0 apple\r\n1 banana\r\n2 cherry\r\n<\/code><\/pre>\n
    Here, it prints each element and its corresponding index in the list fruits<\/strong> on a new line.<\/p>\n
    The enumerate()<\/strong> function returns a tuple, where the first element is the index and the second element is the value of the current item in the loop.<\/p>\n
    Note<\/strong>: When we are looping through a collection, it is a good practice to use the enumerate()<\/strong> function instead of using the range()<\/strong> function with the length of the collection and the index to access the elements directly. This is because it makes your code more readable.<\/p>\n
    For Loop with Else statement<\/h2>\n
    In Python, the for loop can be used in conjunction with an else<\/strong> block<\/a>. The else block is executed after the loop completes, but only if the loop completes normally (i.e., without being interrupted by a break<\/strong> statement).<\/p>\n
    The syntax for a for loop with an else block is as follows:<\/p>\n
    for variable in sequence:\r\n    # code to execute on each iteration\r\nelse:\r\n    # code to execute after the loop completes\r\n<\/code><\/pre>\n
    Example using the above syntax:<\/p>\n
    numbers = [1, 2, 3, 4, 5]\r\nfor num in numbers:\r\n    print(num)\r\nelse:\r\n    print(\"Loop complete.\")\r\n<\/code><\/pre>\n
    The output for this code will be:
    \n1
    \n2
    \n3
    \n4
    \n5
    \nLoop complete.<\/code><\/p>\n
    Here, we are using a for<\/strong> loop with an else<\/strong> block to iterate over a list of numbers and print each one. If the loop completes normally, the else block will print “Loop complete<\/strong>“.<\/p>\n
    This is useful for situations where we want to perform certain actions after the loop completes, but only if the loop completes normally. For example, we might use an else<\/strong> block to check for errors or missing data after processing a large dataset, or to display a message<\/a> to the user after a successful operation.<\/p>\n
    Note: <\/strong>If the loop is interrupted by a break<\/strong> statement, the else<\/strong> block will not be executed. So it’s important to keep that in mind when using else<\/strong> block with for<\/strong> loop.<\/p>\n
    Conclusion<\/h4>\n
    For loops in Python is an essential tool for Python programmers. Whether you are a beginner or an experienced developer, understanding how to use for loops effectively is crucial for writing efficient and effective code.<\/p>\n
    In this article, we’ve covered the basics of the standard for loop<\/strong>, including how to iterate over sequences and use the range()<\/strong> function. We’ve also learned about the “for-each” loop<\/strong> and how it differs from the standard for loop. Then we saw how to use else<\/strong> statements in for loops.<\/p>\n
    There are other types of loops in Python as well<\/p>\n