str Built-in Functions¶

Several built-in functions work naturally with strings.

These functions help inspect, transform, and analyze text.

Common examples include:

• len()
• str()
• sorted()
• reversed()
• enumerate()
• ord()
• chr()

flowchart TD
    A[Built-ins for strings]
    A --> B[len]
    A --> C[sorted]
    A --> D[reversed]
    A --> E[enumerate]
    A --> F[ord/chr]
````

---

## 1. len()

Returns the number of characters in a string.

```python
text = "Python"
print(len(text))

Output:

6

2. str()¶

Converts values to strings.

x = 42
print(str(x))

Output:

42

3. sorted()¶

Returns a sorted list of characters.

text = "cab"
print(sorted(text))

Output:

['a', 'b', 'c']

4. reversed()¶

Returns characters in reverse order.

text = "abc"
print(list(reversed(text)))

Output:

['c', 'b', 'a']

5. enumerate()¶

Pairs indexes with characters.

for i, ch in enumerate("cat"):
    print(i, ch)

Output:

0 c
1 a
2 t

6. ord() and chr()¶

ord() converts a character to its Unicode code point.

chr() converts a code point back to a character.

print(ord("A"))
print(chr(65))

Output:

65
A

7. Worked Examples¶

Example 1: count letters using len¶

word = "banana"
print(len(word))

Example 2: alphabetical characters¶

print(sorted("python"))

Example 3: character code¶

print(ord("z"))

8. Summary¶

Key ideas:

• many built-ins work naturally with strings
• len() measures strings
• sorted() and reversed() operate on characters
• enumerate() pairs indexes with characters
• ord() and chr() connect characters to Unicode integers

Built-in functions complement string methods and expand what can be done with text.