Use placeholders to simplify the splicing and formatting output of strings, making them more concise and easy to read.
In Python, a placeholder is a handy string formatting tool for inserting the value of a variable or expression into a string.
This article will provide a comprehensive introduction to the use of placeholders in Python, including basic placeholders, formatting operators, f-strings, etc., and demonstrate their usage through **. Premium short** plan
For the sake of demonstration, let's define a few variables (which will be used below).
name = "alice" age = 25 height = 1.75
Basic placeholders.
Basic placeholders in Python include %s, %d, %f, etc., and are used to represent types such as strings, integers, and floating-point numbers.
In a string, use a placeholder followed by a variable or expression to insert its value into the corresponding position in the string.
Example**: Insert the string print( using the %s placeholder"my name is %s"% name) output: My name is Alice inserts the integer print( with the %d placeholder"i am %d years old"% age) output: i am 25 years old insert float print( using the %f placeholder"my height is %.2f meters"% height) Output: My height is 175 meters
In this example, we use the %s, %d, and %f placeholders to insert values of the string, integer, and floating-point types, respectively. In this way, it is convenient to insert the value of a variable or expression into a string.
Formatting operators.
In addition to the basic placeholders, Python also provides a format operator for formatting strings. Use formatting operators to give you more flexibility in controlling the output format.
Format the string using the format operator print("my name is {}".format(name)) output: My name is alice print("i am {}years old".format(age)) output: i am 25 years old print("my height is meters".format(height)) output: my height is 175 meters
In this example, we're using {} as a placeholder and passing through. The format() method inserts the value of a variable or expression into a string. Compared to basic placeholders, formatting operators are more flexible and allow you to control the style of the output by specifying the format.
f-string（python 3.6+）
From python 36 onwards, a new way of formatting strings - f-string was introduced. f-string allows the letter "f" or "f" to be preceded by a string and the use of curly braces {} in the string to include the value of a variable or expression.
An example is as follows:
Format the string print(f"my name is ") Output: My name is Alice Print(F"i am years old"Output: I am 25 years old print(f"my height is meters"Output: My height is 175 meters
In this example, we used the f-string to format the string.
Strings can be dynamically formatted by prefixing the string with the letter "f" and including the value of the variable or expression in curly braces {}.
F-string is Python 3The new features of version 6 and above are very convenient to use.
Summary. To sum up, placeholders in Python can help us simplify the splicing and formatting output of strings, making ** more concise and easy to read.
In practical applications, we can choose the appropriate placeholder to deal with the formatting of strings according to our needs.