Python built-in functions (23) -- format, pythonformat

Python built-in functions (23) -- format, pythonformat

English document:

format(Value[,Format_spec])

ConvertValueTo a "formatted" representation, as controlledFormat_spec. The interpretationFormat_specWill depend on the type ofValueArgument, however there is a standard formatting syntax that is used by most built-in types: Format Specification Mini-Language.

The defaultFormat_specIs an empty string which usually gives the same effect as callingstr(value).

A callformat(value, format_spec)Is translatedtype(value).__format__(value, format_spec)Which bypasses the instance dictionary when searching for the value's__format__()Method.TypeErrorException is raised if the method search reachesobjectAndFormat_specIs non-empty, or if eitherFormat_specOr the return value are not strings.

 

Note:

 

1. The function Format a value.

2. If the format_spec parameter is not provided, it will have the same effect as calling str (value) and convert it to string format.

>>> format(3.1415936)'3.1415936'>>> str(3.1415926)'3.1415926'

3. for different types, the values provided by the format_spec parameter are different.

# The parameter 's' None> format ('some string', 's') 'some string'> format ('some string ') 'Some string' # The following parameters can be provided for integer values: 'B' C' d ''o' x' 'n' None >>> format (3, 'B') # convert to binary '11'> format (97, 'C') # convert unicode to character 'a'> format (11, 'D') # convert to a 10-digit '11'> format (11, 'O') # convert to an 8-digit '13'> format (11, 'X') # convert to a hexadecimal lowercase letter to 'B'> format (11, 'x ') # convert to hexadecimal uppercase letters to 'B' >>> format (11, 'n') # Same as d '11' >>> format (11) # The default value is the same as that of d. '11' # Floating Point Numbers can provide the following parameters: 'E' E' F' ''G'' 'n' '%' None. >>> format (314159267, 'E') # scientific notation. The default value is 6 decimal places. 141593e + 08 '> format (314159267, '0. 2e') # scientific notation, specifying to retain 2 decimal places '3. 14e + 08 '> format (314159267, '0. 2e') # scientific notation, specifying to retain 2 decimal places, using uppercase E to represent '3. 14E + 08 '> format (314159267, 'F') # decimal point counting method. The default value is 6 decimal places '123. 000000 '>>> format (3.14159267000, 'F') # number of decimal points. The default value is 6 decimal places. 141593 '> format (3.14159267000, '0. 8f') # decimal point counting method, which specifies to keep 8 decimal places '3. 14159267 '> format (3.14159267000, '0. 10f') # decimal point notation, which specifies to retain 10 decimal places. 1415926700 '>>> format (3.14e + 1000000, 'F') # indicates the decimal point count. The infinite number is converted to the 'inf' # g format, assume that p is the number of reserved decimal places specified in the format. First, use the scientific notation to format it to obtain the power index exp. If-4 <= exp <p, use the decimal notation, and keep the p-1-exp decimal places, otherwise count by decimal notation, and retain the decimal places by p->> format (0.00003141566 ,'. 1G ') # p = 1, exp =-5 = "-4 <= exp <p is not true, counting by scientific notation, retain the 0 decimal point '3e-05 '> format (0.00003141566 ,'. 2G ') # p = 1, exp =-5 = "-4 <= exp <p is not true, count by scientific notation, retain 1 decimal point '3. 1e-05 '>>> format (0.00003141566 ,'. 3G ') # p = 1, exp =-5 = "-4 <= exp <p is not true, count by scientific notation, retain 2 decimal places '3. 14e-05 '>>> format (0.00003141566 ,'. 3G ') # p = 1, exp =-5 = "-4 <= exp <p is not true, count by scientific notation, retain 0 decimal places, e. Use uppercase letters. 14E-05 '>>> format (3.1415926777 ,'. 1G ') # p = 1, exp = 0 = "-4 <= exp <p is true, counting by decimal notation, keep the 0 decimal point '3'> format (3.1415926777 ,'. 2G ') # p = 1, exp = 0 = "-4 <= exp <p is true, count by decimal notation, retain 1 decimal point '3. 1 '> format (3.1415926777 ,'. 3G ') # p = 1, exp = 0 = "-4 <= exp <p is true, count by decimal notation, retain 2 decimal places '3. 14'> format (0.00003141566 ,'. 1n') # Same as g '3e-05 '> format (0.00003141566 ,'. 3n') # The same as g '3. 14e-05 '>>> format (0.00003141566) # Same as g' 3. 141566e-05'