Python standard library: built-in Function format (value [, format_spec])

Python standard library: built-in Function format (value [, format_spec])

This function formats the value in the format of format_spec. However, the function explains that format_spec is determined by the value type. Different types have different formatting interpretations. When the format_spec parameter is null, this function is equivalent to the str (value) function.

In fact, this function is called to convert format (value, format_spec) to type (value ). the _ format _ (format_spec) method is called. Therefore, the _ format _ () method is searched for in the value type. If this method is not found, an exception TypeError is returned.

The format_spec format is as follows:

Format_spec: = [[fill] align] [sign] [#] [0] [width] [,] [. precision] [type]

Fill: =

Align: = <| >|=| ^

Sign: = + |-|

Width: = integer

Precision: = integer

Type: = B | c | d | e | E | f | F | g | G | n | o | s | x | X | %

Fill indicates that any character can be entered.

Align is the Alignment Method, <is the left alignment,> is the right alignment, and ^ is the center alignment.

Sign is a symbol, + indicates a positive number, and-indicates a negative number.

Width indicates the total number of output digits.

Precision is the number of decimal reserved digits.

Type indicates the expression of the output numeric value. For example, B Indicates binary, E indicates exponential, and X indicates hexadecimal.

Example:

 

#format()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'))print(format('test', '^20'))

 

The output is as follows:

2918

500

0000003.14

03.14

3.141590E + 00

Test

Test

Test