Python str(): Convert Values to Strings

The str() function converts an object into a string representation. It’s useful for displaying information, formatting text, and converting numbers or objects into readable strings.

Example

num = 42
print(str(num))

Output:

'42'

Converts the integer 42 into a string.

Syntax

str(object="")

• object (optional) → The value to convert into a string.
• Returns → A string representation of the object.

1. Converting Numbers to Strings

print(str(100))     # Output: '100'
print(str(3.14))    # Output: '3.14'
print(str(-42))     # Output: '-42'

Works with integers and floats.

2. Converting a List, Tuple, or Dictionary to a String

print(str([1, 2, 3]))  # Output: '[1, 2, 3]'
print(str((4, 5, 6)))  # Output: '(4, 5, 6)'
print(str({"a": 1}))   # Output: "{'a': 1}"

Formats data structures as readable strings.

3. Using str() on Booleans and None

print(str(True))   # Output: 'True'
print(str(False))  # Output: 'False'
print(str(None))   # Output: 'None'

Converts Booleans and None into strings.

4. Custom String Representation for Objects

class Person:
    def __init__(self, name):
        self.name = name

    def __str__(self):
        return f"Person: {self.name}"

p = Person("Alice")
print(str(p))  # Output: Person: Alice

Defines a human-readable string for a class.

5. Formatting Strings with str()

age = 25
print("My age is " + str(age))  
# Output: My age is 25

Needed when concatenating numbers with strings.

6. Using str() with File Handling

data = 3.14159
with open("output.txt", "w") as file:
    file.write(str(data))  # Write as text

Ensures data is saved as a string.

7. str() vs repr() (Human vs Debugging Format)

Function	Purpose	Example Output
str()	User-friendly	‘Hello\nWorld’ → Hello World
repr()	Debugging	‘Hello\nWorld’ → ‘Hello\\nWorld’

text = "Hello\nWorld"
print(str(text))  # Output: Hello
                 #         World

print(repr(text))  # Output: 'Hello\nWorld'

Key Notes

• ✔ Converts any object to a string.
• ✔ Used in formatting, file handling, and logging.
• ✔ Works with numbers, lists, dictionaries, and classes.
• ✔ Use repr() instead for debugging.

By using str(), you can convert values into readable text, format output, and store data as strings. 🚀