String formatting
There are two ways to format a Python string: a percent-semicolon, format-mode
The percent of the semicolon is relatively old, and format is a more advanced way to replace the old way, the two coexist. [PEP-3101]
This PEP proposes a new system for built-in string formatting operations, intended as a replacement for the existing '% ' s Tring formatting operator.
1, percent of the way
%[(name)][flags][width]. [Precision]typecode
- (name) optional, used to select the specified key
- Flags are optional, and the values to choose from are:
- + Right-aligned, positive plus, negative before plus minus;
- -left-justified; no sign before positive number, plus minus sign before negative number;
- Spaces are right-justified, plus a positive number before a negative number plus a minus sign;
- 0 Right alignment, no sign before positive number, minus sign before negative, and 0 padding in blank
- Width selectable, occupied widths
- . Precision optional, number of digits retained after the decimal point
- TypeCode must choose
- S, gets the return value of the __str__ method of the passed-in object and formats it to the specified location
- R, gets the return value of the __repr__ method of the passed-in object and formats it to the specified location
- C, Integer: Converts a number to its Unicode corresponding value, 10 binary range is 0 <= i <= 1114111 (py27 only supports 0-255); character: add character to specified position
- O, converts an integer to an octal representation and formats it to a specified location
- X, converts an integer to a hexadecimal representation and formats it to a specified location
- D, converts an integer, floating-point number to a decimal representation, and formats it to a specified position
- E, converting integers, floating-point numbers to scientific notation, and formatting them to a specified location (lowercase e)
- E, converting integers, floating-point numbers into scientific notation, and formatting them to a specified position (uppercase E)
- F, converts an integer, floating-point number to a floating-point number representation, and formats it to a specified position (the default is 6 digits after the decimal point)
- F, ibid.
- G, auto-adjust convert integers, floating-point numbers to floating-point or scientific notation (more than 6 digits in scientific notation), and format them to a specified location (if scientific counts are e;)
- G, auto-adjust convert integers, floating-point numbers to floating-point or scientific notation (more than 6 digits in scientific notation), and format them to a specified location (if scientific counts are e;)
- %, when there is a format flag in the string, a percent sign is required
Note: There is no way to automatically convert an integer to a binary representation in Python with a percent-semicolon format
Common formatting:
TPL = "I am%s"% "Alex" TPL = "I am%s age%d"% ("Alex", +) TPL = "I am% (name) s age% (age) d"% {"name": "Alex", "Age": The TPL = "percent%.2f"% 99.97623 TPL = "I am% (PP)." 2f "% {" pp ": 123.425556,} TPL =" I am%.2f percent "% {" pp ": 123.425556, }
Python develops string formatting for "first" Python basics
