Detailed explanation of format() method in Python

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Detailed explanation of the format() method in Python

In Python, the formatted output string uses the format() function. Strings are classes, and you can use methods;

Python is a completely object-oriented language. Everything is an object;

The parameters of the string are represented by {NUM}, 0, represents the first parameter, 1, represents the second parameter, will be used in the future times increment;

Use ":" to specify the operations required to represent the element, such as ":.3" with three decimal places, ":8" taking up 8 character space, etc.;

You can also add specific letters, such as:

1. 'b' - binary. Output the number in base 2.

2. 'c' - Character. Convert the integer to the corresponding Unicode string before printing.

3. 'd' - Decimal integer. Convert the number to base 10 Output.

4. 'o' - Octal. Output numbers in base 8.

5. 'x' - Hexadecimal . Output the number in base 16, and use lowercase letters for digits above 9.

6. 'e' - Power symbol. Print the number in scientific notation, represented by 'e' Power.

7. 'g' - General format. Output the value in fixed-point format. When the value is particularly large, print it in power form.

8. 'n' - Number. Same as 'd' when the value is an integer, and the same as 'g' when the value is a floating point number. The difference is that it inserts a number separator according to the locale.

9. '%' - Percentage. Multiply the value by 100 and print it in fixed-point ('f') format, with a percent sign after the value.

Numbers (0, 1, ...) represent the elements in format(), so you can use "." to call the element method;

The code is as follows:

# -*- coding: utf-8 -*- 
 
#==================== 
#File: abop.py 
#Author: Wendy 
#Date: 2013-12-03 
#==================== 
 
#eclipse pydev, python3.3 
 
age = 25 
name = 'Caroline' 
 
print('{0} is {1} years old. '.format(name, age)) #输出参数 
print('{0} is a girl. '.format(name)) 
print('{0:.3} is a decimal. '.format(1/3)) #小数点后三位 
print('{0:_^11} is a 11 length. '.format(name)) #使用_补齐空位 
print('{first} is as {second}. '.format(first=name, second='Wendy')) #别名替换 
print('My name is {0.name}'.format(open('out.txt', 'w'))) #调用方法 
print('My name is {0:8}.'.format('Fred')) #指定宽度

Output:

Caroline is 25 years old.  
Caroline is a girl.  
0.333 is a decimal.  
_Caroline is a 11 length.  
Caroline is as Wendy.  
My name is out.txt 
My name is Fred  .

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