What does format in python mean?

Format in Python is a string formatting method used to insert variables or values ​​into placeholder positions in a string. Through the format method, we can dynamically construct a string to contain different values.

format in Python is a string formatting method used to insert variables or values ​​into placeholder positions in a string. Through the format method, we can dynamically construct a string to contain different values.

In Python In versions 2.6 and later, the format method uses a pair of curly braces ({}) as placeholders, which can contain format specifiers. In the format string, the number of curly braces must correspond to the number of arguments passed to the format method. These placeholders will be replaced by the parameter values ​​passed in the format method.

The following are some examples demonstrating the usage of format:

1. Simple string interpolation

name = "Alice"
age = 25
print("My name is {} and I am {} years old.".format(name, age))

Output:

My name is Alice and I am 25 years old.

2. Formatting Specifier

number = 3.1415926
print("The value of pi is {:.2f}.".format(number))

Output:

The value of pi is 3.14.

In this example, {:.2f} means to format a floating-point value to a floating-point number with two digits after the decimal point.

3. Positional parameters and keyword parameters

name = "Bob"
age = 30
print("My name is {0} and I am {1} years old. {name} is my 
friend.".format(name, age, name="Alice"))

Output:

My name is Bob and I am 30 years old. Alice is my friend.

In this example, {0} and {1} represent positional parameters, corresponding to the format method respectively the first and second parameters in . name="Alice" is a keyword argument that can be used anywhere in the string.

4. Use dictionary for formatting

person = {"name": "Charlie", "age": 35}
print("My name is {name} and I am {age} years old.".format(**person))

Output:

My name is Charlie and I am 35 years old.

In this example, two asterisks (**) are used to format the key values ​​​​in the dictionary The pair is passed as a parameter to the format method.

In short, format is a powerful string formatting method in Python that can dynamically construct a string based on the value of the variable and the format specifier. It provides a variety of flexible usages, allowing us to manipulate strings in a more concise and readable way .

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