Tutorials

Python string format() Method

Posted in Python Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 62 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In Python, the format() method is a versatile and powerful tool for formatting strings.

It allows you to create dynamic strings by inserting values into placeholders within a string template.

In this tutorial, we'll explore the syntax, usage, and various features of the format() method in Python.

💡 Syntax

The syntax for the format() method is as follows:

Syntax

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string.format(value1, value2, ...)

string: The string containing placeholders to be replaced.
value1, value2, ...: Values to be inserted into the placeholders.

📄 Example

Let's start with a basic example to illustrate how the format() method works.

format.py

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# Example 1
name = "Alice"
age = 30
sentence = "My name is {} and I am {} years old.".format(name, age)
print("Example 1:", sentence)

💻 Testing the Program

Output

Example 1: My name is Alice and I am 30 years old.

🧠 How the Program Works

In Example 1, the format() method replaces the curly braces {} in the string with the values of name and age, resulting in the output: My name is Alice and I am 30 years old.

↩️ Return Value

The format() method does not return a new string; instead, it modifies the original string in place. Therefore, the return value is None. Keep this in mind when using the format() method within expressions.

📚 Common Use Cases

Placeholder Indexing:

You can use numerical indices inside the curly braces to specify the order of the values.
placeholder-indexing.py
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```
# Example 2
item1 = "apple"
item2 = "banana"
sentence = "I have {1} and {0}.".format(item1, item2)
print("Example 2:", sentence)
```
💻 OutPut
Output
```
Example 2: I have banana and apple.
```
🧠 How the Program Works

In Example 2, the values of item1 and item2 are inserted based on their index positions, resulting in the output: "I have banana and apple."
Named Placeholders:

Named placeholders provide a clear way to specify which value corresponds to which placeholder.
named-placeholders.py
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```
# Example 3
sentence = "The {fruit} is {adjective}.".format(fruit="orange", adjective="delicious")
print("Example 3:", sentence)
```
💻 OutPut
Output
```
Example 3: The orange is delicious.
```
🧠 How the Program Works

In Example 3, named placeholders fruit and adjective are replaced with the specified values, resulting in the output: "The orange is delicious."
Formatting Numbers:

The format() method allows you to control the formatting of numerical values.
formatting-numbers.py
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```
# Example 4
price = 19.95
formatted_price = "The price is ${:.2f}.".format(price)
print("Example 4:", formatted_price)
```
💻 OutPut
Output
```
Example 4: The price is $19.95.
```
🧠 How the Program Works

In Example 4, the :.2f inside the placeholder formats the price as a floating-point number with two decimal places, resulting in the output: "The price is $19.95."

📝 Notes

The format() method is more flexible and recommended over the older % formatting method.
Python 3.6 introduced f-strings, which provide a more concise and readable way to format strings. However, the format() method remains a powerful option.

🎢 Optimization

The format() method is optimized for performance and readability. However, if you are working with Python 3.6 or later, you may consider using f-strings for even more concise and readable string formatting

f-strings.py

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# Using f-strings (Python 3.6+)
name = "Bob"
age = 25
formatted_string = f"Hello, my name is {name} and I'm {age} years old."
print(formatted_string)

🎉 Conclusion

The format() method in Python is a versatile and essential tool for string formatting. Whether you're dealing with simple substitutions or complex formatting requirements, the format() method provides a robust solution.

Feel free to experiment with different string templates and values to explore the full capabilities of the format() method. Happy coding!