> For the complete documentation index, see [llms.txt](https://kallyasmedia.gitbook.io/cit-python-cohort-three/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kallyasmedia.gitbook.io/cit-python-cohort-three/week2/if_statements.md).

# Control Flow / If Statements

Use `if` statements to run code only when a condition is true. The `elif` and `else` clauses are optional.

## Syntax

```python
if condition:
    # run if condition is true
elif another_condition:
    # run if previous conditions were false
else:
    # run if all conditions were false
```

## Example

```python
x = 10

if x < 0:
    print("Negative")
elif x % 2 != 0:
    print("Positive and odd")
else:
    print("Even or zero")
```

## Truthiness

In a boolean context, these values are considered false:

* `0`, `0.0`
* `None`
* empty strings, lists, tuples, dicts, and sets

Everything else is considered true. The most Pythonic way to test a value is:

```python
if x:
    print("x is truthy")
```

Avoid:

```python
if x is True:
    ...
```

## Common Pitfalls

* Forgetting the colon `:` after the condition.
* Missing indentation inside the block.
* Comparing directly to `True` or `False` unnecessarily.

## Practice

1. Write a program that prints `"adult"` if `age >= 18`, otherwise `"minor"`.
2. Extend it to print `"senior"` if `age >= 65`.

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