The **`isalnum`** method checks if all the characters of a string are *alphanumeric*. If the string  contains only alphanumeric characters, then `isalnum` returns `True`; otherwise, it returns `False`. 

Alphanumeric characters include:

* Alphabets (a-z) (A-Z)
* Numbers 0-9
* Subscript, superscript
* Fractions
* Roman numerals


#   
## Syntax

```
string.isalnum()
```

## Return value

* The function returns `True` if all characters of the string are alphanumerical.

* The function returns `False` if even one character of the string is not an alphanumeric character or if the string is empty.

## Example 1

```python
string = "123abc"
string.isalnum() #True
```
In the string above, `123abc`, all the characters are alphanumeric, so the function returns `True`.

## Example 2

```python
string = "123 abc"
string.isalnum() #False
```
In the string above, `123 abc`, the space is not an alphanumeric character, so `isalnum()` returns `False`.

## Example 3

```python
string = ""
string.isalnum() #False
```
The `isalnum` method returns `False` for an empty string.

## Example 4
```python
string = "½"
string.isalnum() #True
```
`isalnum` returns `True` for the `½` string because fractions are considered alphanumeric characters.

## Code

string = "123abc"
print(string, "  isalnum --> ", string.isalnum())

string = "123 abc"
print(string, "  isalnum --> ", string.isalnum())

string = ""
print(string, "isalnum -->", string.isalnum())

string = "½"
print(string, "isalnum -->", string.isalnum())

What is string.isalnum in Python? 

isalnum checks if all string characters are alphanumeric; returns True if they are, otherwise False.