Python Input Output

Input and output are how your program communicates with a user through the terminal.

- **Output**: `print()`
- **Input**: `input()`

## Printing output

```python
print("Hello World")
print("Welcome", "to", "Python")

print("""Line 1
Line 2
Line 3""")
```

Expected output:

```
Hello World
Welcome to Python
Line 1
Line 2
Line 3
```

## Getting user input

```python
name = input("What's your name? ")
print(f"Hello {name}!")
```

Example:

```
What's your name? Rachel
Hello Rachel!
```

## Very important concept: input() returns a string

Even when a user types `20`, Python reads it as text.

```python
age_text = input("Enter your age: ")
print(type(age_text))
```

Example:

```
Enter your age: 20
<class 'str'>
```

So you convert:

```python
age = int(age_text)
```

## Type conversion example with logic

```python
age = int(input("Enter your age: "))

if age >= 18:
    print("You're an adult.")
else:
    print("You're under 18.")
```

Example:

```
Enter your age: 15
You're under 18.
```

## Print formatting: sep and end

```python
print("apple", "banana", "cherry", sep=", ")
print("Loading", end="...")
print("Done!")
```

Expected output:

```
apple, banana, cherry
Loading...Done!
```

## Graph: input to output

```mermaid
flowchart TD
  A[input()] --> B["string value"]
  B --> C[int()/float() if needed]
  C --> D[logic]
  D --> E[print output]
```

In the next lesson, you will learn file handling so your program can save and read information from disk.