Python Learning (iii)

Chapter III Using Strings

3.1 Basic string manipulation

Sequence Operations (index, Shard, multiply, Judge membership, length, maximum, minimum) apply to a string, but the string is immutable, so the Shard assignment is illegal.

3.2 String Formatting: Lite version

% is a string formatting operator

Usage: Place a string (formatted string) on the left side and the value you want to format on the right. You can use a value (such as a string or a number), or you can use a tuple or dictionary of multiple values.

>>> Print ("%s is%s years old"% ("FSDFSD", 56))
FSDFSD is years-old

>>> format = "%s is%s years old"
>>> values = ("Robin", 34)
>>> print (format% values)
Robin is-years old

Note: Only tuples and dictionaries can format more than one value, and if you use lists or other sequences instead of tuples, the sequence will be interpreted as a value.

>>> Print ("%s is%s years old"% (["FSDFSD", 56],45))
[' FSDFSD ', ' years

Note: If you want to include a percent semicolon in a formatted string, you must use

If you are formatting real numbers (floating-point numbers), you can use F to describe the type of conversion specifier, providing precision, a period plus the number of decimal digits you want to keep:

>>> format = "PI with three decials:%.3f"
>>> from Math import pi

>>> print (format% pi)
PI with three decials:3.142

3.3 String Formatting: Full version

If the right operand is a tuple or a dictionary, each of these elements is individually formatted, and each value requires a conversion specifier.

>>> "%s%s%s"% (per-cent)
' 1 2 3 '

3.3.1 Simple Conversion

>>> "%d"% 42
' 42 '

>>> "%x"% 42
' 2a '

>>> "%f"% pi
' 3.141593 '

3.3.2 Field width and precision

Field width: The minimum number of characters retained by the converted value.

Precision: Number of decimal digits of the result

>>> "%10.2f"% pi//width is 10, accuracy is 2
' 3.14 '

3.3.3 symbol, for alignment with 0 padding

>>> '%010.2f '% pi//width is 10, filled with 0
' 0000003.14 '

>>> "%-10.2f"% pi//left Justified
' 3.14 '

>>> "% 5d"% 10//space, indicating positive number preceded by a space.
' 10 '

>>> "%+5d"% 10//+ sign, indicating whether it is a plus or minus number, displays the symbol
' +10 '

3.4 String method

3.4.1 Find the location of the substring, if not returned-1

>>> "FSDFSDFSDFDSF". Find ("FSD")
0

>>> "FSDFSDFSDFDSF". Find ("FSD", 1,5)//provide start and end points ( Note: Contains the previous index, does not contain the latter index, which is the Python idiom -1 Law ).

RFind ()/index ()/Rindex ()/count ()/StartsWith ()/EndsWith ()

3.4.2 The elements in the join sequence

The concatenated sequence must be a string

>>> "abc". Join ("de")
' DABCE '

3.4.3 Lower returns the lowercase version of the string

>>> "ABc". Lower ()
' ABC '

>>> "Sdfdfds". Capitalize ()//First Letter Capital
' Sdfdfds '

>>> "ABC". Swapcase ()//uppercase to lowercase, lowercase to uppercase
' ABC '

' FDSFSD '
>>> "ABC def ght". Title ()//capitalize the first letter of all words
' ABC Def Ght '

Upper ()//uppercase

All occurrences of the 3.4.4 replace string are replaced

>>> "This was a test". Replace ("is", "EEZ")
' Theez eez a test '

Inverse method of 3.4.5 split Join method

>>> "I am Robin". Split ("")
[' I ', ' am ', ' Robin ']

3.4.6 Strip A string that removes white space on both sides (not including interior)

>>> "FSF ASFA". Strip ()
' FSF ASFA '

3.4.7 Translate

Similar to replace, a different place is to replace only a single character

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