eolas/zk/Loops_in_Python.md

---
tags: [python]
---

# Loops in Python

## For

There are three main types of `for` loop in Python and they all use the
`for...in` clause:

1. Traditional `for` loop with range:

   ```py
   for i in range(0, 5):
       print(i)
   ```

   This is equivalent to the following in JavaScript:

   ```js
   for (let i = 0; i <= 5: i++) {
       console.log(i)
   }
   ```

2. `for` loop with iterable:

   ```py
   fruits = ["apple", "banana", "cherry"]
   for (fruit in fruits):
       print(fruit)
   ```

3. `for` loop with `enumerate()` function: Iterate over an iterable whilst also
   keeping track of the index of the current element:
   ```py
   for index, fruit in enumerate(fruits):
       print(f"Index {index}: {fruit}")
   ```

### Loop in increments greater than 1

The following loop increments by 2 on each iteration

```py
for i in range(0, 10, 2):
    print(i, ' ', end='')
print()

# 0  2  4  6  8
```

### Break and continue

#### Break

```py
num = int(input('Enter a number from 1-6 to check for: '))
for i in range(0, 6):
    if i == num:
        break
    print(i, ' ')
```

#### Continue

```py
for i in range(0, 10):
    print(i, ' ', end='')
    if i % 2 == 1:
        continue
    print('hey its an even number')
    print('we love even numbers')
print('Done')

"""
0  hey its an even number
we love even numbers
1  2  hey its an even number
we love even numbers
3  4  hey its an even number
we love even numbers
5  6  hey its an even number
we love even numbers
7  8  hey its an even number
we love even numbers
9  Done
"""
```

## While

```python
count = 0
print('Starting')
while count < 10:
    print(count, '', end='')
    count += 1

print()  # not part of the while loop
print('Done')

"""
Starting
0 1 2 3 4 5 6 7 8 9
Done
"""
```

> There are no `do while` loops in Python