Loops in Python

Loops are a fundamental concept in programming, allowing for the execution of a block of code multiple times. Python provides for and while loops to iterate over a sequence of items. This blog will guide you through their syntax and use cases, enhancing your automation and processing capabilities.

For Loops

The for loop in Python is used to iterate over a sequence (like a list, tuple, dictionary, set, or string). It’s more like an iterator method as found in other object-orientated programming languages.

Example:

for i in range(5):
    print(i)

This will output the numbers 0 to 4 on separate lines.

While Loops

The while loop in Python allows for repeated execution as long as an expression is true.

Example:

count = 0
while count < 5:
    print(count)
    count += 1

This will output the numbers 0 to 4 on separate lines, similar to the for loop example.

Nested Loops

You can use one or more loop inside any another for or while loop.

Example:

for i in range(3):
    for j in range(2):
        print(i, j)

This will output: 0 0 0 1 1 0 1 1 2 0 2 1

Loop Control Statements

Loop control statements change the execution from its normal sequence. When execution leaves a scope, all automatic objects that were created in that scope are destroyed. Python supports the following control statements:

• break: Terminates the loop statement and transfers execution to the statement immediately following the loop.
• continue: Causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating.
• pass: Used when a statement is required syntactically but you do not want any command or code to execute.

Example using break:

for val in "string":
    if val == "i":
        break
    print(val)

Output will be: s t r

By understanding and utilizing these loops, you can make your Python scripts more efficient and concise.