Python str Operation Method

Python str Operation Method

1. str. format (): format the string using the "{}" Placeholder (the index number format and key-value pairs in the placeholder can be used together ).

>>> String = 'python {}, django {}, tornado {}'. format (2.7, 'web', 'tornado ') # The number of {} placeholders corresponds to the number of values, which are entered in the string in order.

>>> String

'Python2.7, djangoweb, tornadotornado'

>>> String = 'python {}, django {}, tornado {} '. format (2.7, 'web ')

Traceback (most recent call last ):

File "", line 1, in

String = 'python {}, django {}, tornado {} '. format (2.7, 'web ')

IndexError: tuple index out of range

>>> String = 'python {0}, django {2}, tornado {1 }'. format (2.7, 'web', 'tornado ') # You can also specify the value to be entered (starting from 0, the subsequent values may not always be used, however, make sure that the specified position has a value)

>>> String

'Python2.7, djangotornado, tornadoweb'

>>> String = 'python {py}, django {dja}, tornado {tor }'. format (tor = 'tornado ', dja = 'web', py = 2.7) # values can be assigned using key-value pairs.

>>> String

'Python2.7, djangoweb, tornadotornado'

>>>

Python str Operation Method

2. Use "%" to format the string.

Format a symbol table

% C to single character

% R is converted to a string expressed by repr ().

% S is converted to a string expressed by str ().

Convert % d or % I to a signed decimal integer

% U to an unsigned decimal integer

% O to an unsigned octal integer

% X is converted into an unsigned hexadecimal integer. The hexadecimal letter is in lowercase.

% X is converted into an unsigned hexadecimal integer, and hexadecimal letters are written in uppercase.

% E is converted to a floating point number expressed in scientific notation, where e is expressed in lowercase.

% E is converted into a floating point number expressed in scientific notation, where E is expressed in uppercase.

% F or # F convert to floating point number

% G is automatically converted to % e or % f by Python based on the number size.

% G is automatically converted to % E or % F by Python based on the number size.

% Output "%"

Auxiliary formatting symbol table

* Defines the width or decimal point precision.

-Left alignment

+ Positive number output positive value symbol "+"

When the number size is less than m. n, fill in space

# Display 0 before the octal digit, and 0x or 0X before the hexadecimal digit

When the size of 0 numbers is less than m. n, use 0 to fill

M. nm is the minimum total display width, and n is the number of digits after the decimal point (if available)