Loops
Loops allow you to execute code multiple times.
for Loop: Iterates over a sequence (list, string, range, etc.)
while Loop: Continues while a condition is True.
Loop Control:
- break: Exit the loop
- continue: Skip to next iteration
- pass: Do nothing (placeholder)
range() Function: Generates a sequence of numbers:
- range(5): 0, 1, 2, 3, 4
- range(1, 6): 1, 2, 3, 4, 5
- range(0, 10, 2): 0, 2, 4, 6, 8
enumerate(): Get both index and value when looping.
zip(): Loop over multiple sequences together.
Code Examples
Python Loopspython
# for loop with range
print("Counting to 5:")
for i in range(1, 6):
print(i)
# for loop with list
colors = ["red", "green", "blue"]
print("\nColors:")
for color in colors:
print(color)
# enumerate for index and value
print("\nWith index:")
for index, color in enumerate(colors):
print(f"{index}: {color}")
# while loop
count = 0
print("\nWhile loop:")
while count < 3:
print(f"Count: {count}")
count += 1
# break and continue
print("\nBreak at 3:")
for i in range(1, 6):
if i == 3:
break
print(i)
print("\nSkip even numbers:")
for i in range(1, 6):
if i % 2 == 0:
continue
print(i)
# zip - loop multiple lists
names = ["Alice", "Bob"]
ages = [25, 30]
print("\nZip example:")
for name, age in zip(names, ages):
print(f"{name} is {age}")
# List comprehension
squares = [x**2 for x in range(1, 6)]
print(f"\nSquares: {squares}")List comprehensions are a Pythonic way to create lists from loops in a single line.
Quick Quiz
1. What does range(1, 5) produce?
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