## Type Casting in Python

Type casting is a method used to change the data type of a variable to match the operation you want to perform. In Python, you can use built-in functions like `int()`, `str()`, `float()`, etc., to achieve this.

### Convert an Integer to a Float

You can convert an integer to a float using the `float()` function.

```python
Python 3.12.4 (tags/v3.12.4:8e8a4ba, Jun  6 2024, 19:30:16) [MSC v.1940 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> num = 100  # integer
>>> num = float(num)  # convert to float
>>> print(num)
100.0
>>> print(type(num))
<class 'float'>
```

Here, the integer `100` is converted to a float `100.0`.

### Convert a Float to an Integer

You can convert a float to an integer using the `int()` function.

```python
>>> num = 99.9  # float
>>> num = int(num)  # convert to integer
>>> print(num)
99
>>> print(type(num))
<class 'int'>
```

In this example, the float `99.9` is converted to the integer `99`.

### Convert a String Literal to an Integer and a Float

You can convert a string literal to an integer and a float using `int()` and `float()`.

```python
>>> s = '132'  # string
>>> n = int(s)  # convert to integer
>>> print(n)
132
>>> print(type(n))
<class 'int'>
>>> f = float(s)  # convert to float
>>> print(f)
132.0
>>> print(type(f))
<class 'float'>
```

Here, the string `'132'` is converted to the integer `132` and the float `132.0`.

### Note on Converting Strings with Decimals

If your string contains a decimal point, you can't directly convert it to an integer. First, convert the string to a float and then to an integer.

```python
>>> s = '132.564'  # string
>>> n = int(float(s))  # convert to integer
>>> print(n)
132
>>> print(type(n))
<class 'int'>
```

In this case, the string `'132.564'` is first converted to the float `132.564` and then to the integer `132`.

## Useful Built-in Functions

Python comes with several built-in functions that you can use right away. Here are some of the most useful ones:

### `len()` Function

The `len()` function returns the number of characters in a string.

```python
>>> print(len('hello'))
5
```

This function counts the number of characters in the string `'hello'`, which is `5`.

### `bin()` Function

The `bin()` function converts an integer to its binary representation.

```python
>>> num = 100
>>> print(bin(num))  # print binary number
0b1100100
```

The integer `100` is converted to its binary representation `0b1100100`.

### `oct()` Function

The `oct()` function converts an integer to its octal representation.

```python
>>> num = 100
>>> print(oct(num))  # print octal number
0o144
```

The integer `100` is converted to its octal representation `0o144`.

### `hex()` Function

The `hex()` function converts an integer to its hexadecimal representation.

```python
>>> num = 100
>>> print(hex(num))  # print hex number
0x64
```

The integer `100` is converted to its hexadecimal representation `0x64`.

### `round()` Function

The `round()` function returns a floating-point number rounded to a specified number of decimal places.

```python
>>> num = round(5.12345, 2)
>>> print(num)
5.12
```

Here, the number `5.12345` is rounded to `5.12`.

### `id()` Function

The `id()` function returns a unique identifier for an object, which is its memory address.

```python
>>> num = 5.12
>>> print(id(num))
1562211743472
```

The `id()` function returns the memory address of the object `num`.

These examples demonstrate how you can use type casting and built-in functions to manipulate and format data in Python.