快速了解Python中format函数的使用

Python format() Function Overview

The format() function in Python is a built-in function used for string formatting. It allows the insertion of specified values into a string by replacing placeholders represented by {}. The function follows the syntax:

str.format(*args, **kwargs)

*args and **kwargs are optional parameters representing one or more values to insert and one or more key-value pairs, respectively.

Examples of format() Function Usage

No Parameters

s = "Hello, {}!"
print(s.format("world"))  # Output: Hello, world!

Positional Arguments

s = "I am {} years old and my name is {}."
print(s.format(25, "John"))  # Output: I am 25 years old and my name is John.

Keyword Arguments

s = "My name is {name} and I am {age} years old."
print(s.format(name="John", age=25))  # Output: My name is John and I am 25 years old.

Mixing Positional and Keyword Arguments

s = "My name is {name} and I am {0} years old."
print(s.format(25, name="John"))  # Output: My name is John and I am 25 years old.

Using Dictionaries as Keyword Arguments

person = {"name": "John", "age": 25}
s = "My name is {name} and I am {age} years old."
print(s.format(**person))  # Output: My name is John and I am 25 years old.

Using Indexes

s = "The {2} of {0} is {1:.2f}"
print(s.format("pi", 3.14159, "circle"))  # Output: The circle of pi is 3.14

Additional Examples

print(format(2918))
print(format(0x500, 'X'))
print(format(3.14, '0=10'))
print(format(3.14159, '05.3'))
print(format(3.14159, 'E'))
print(format('test', '20'))
print(format('test', '^20'))

2918

500

00000003.14

03.14

3.141590E+00

test

test

Conclusion

The format() function is essential for conveniently inserting various values into strings, enriching and adding flexibility to string content in Python.

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