Day 3: Loops and Basic String Operations

Loops

Loops allow you to perform repetitive actions in your code. There are two main types of loops in Python: for and while.

1. for loop: used to iterate over a sequence (eg list, tuple, string).
Example:

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

In this example, i will take values ​​from 0 to 4, and on each iteration of the loop, the value i.

2 will be output. while loop: executes a block of code while the condition is true.
Example:

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

In this example, the loop will run as long as the value of x is less than 5. On each iteration of the loop, the value of x will be printed, and x will be incremented by 1.

Basic string operations

1. Concatenation (string addition): Use the + operator to concatenate strings.

name = "John" surname = "Doe" full_name = name + " " + surname print(full_name) # "John Doe" 

2. String multiplication: use the * operator to repeat a string a specified number of times.

hello = "Hello! " greeting = hello * 3 print(greeting) # "Hello! Hello! Hello! "

3. String character access: Use square brackets [] and character index.

text = "Python" first_letter = text[0] print(first_letter) # "P"

4. Line slicing: Use square brackets [] and colon : to indicate the start, end, and stride of the slicing.

text = "Python" slice_text = text[1:4] # Slice from index 1 to 3 (not including 4) print(slice_text) # "yth"

You are now familiar with loops and basic string operations in Python. In the next lesson, we'll look at lists, tuples, and sets.