Python string format output%d,%s and Format function

Legacy formatting:%s,%d

1. Fill in the formatted content sequentially

s = "Hello%s, hello%d"% ("World", "page") print (s)

Result: ' Hello World, hello 100 '

2. Use keyword parameters

s= "% (name) s age% (age) d"%{"name": "Tom", "Age": 10}
Print (s)

Result: Tom name 10

Commonly used formatting symbols

%s corresponds to string type (str)
%d (int) corresponding to the decimal integer type

%f corresponding floating-point number (float)

%r corresponding string (repr)

Using the format () function

1. No parameter condition

s = "Hello {}, hello {}". Format ("World", "Python") print (s)

Result: "Hello World, Hello Python"

2. Position parameters

s = "Hello {1}, hello {0}". Format ("World", "Python") print (s)

Result: "Hello Python, Hello World"

3. Key parameters

s = "Hello {first}, Hello{second}". Format (first= "World", second= "Python") print (s)

Result: "Hello World, Hello Python"

4, position parameters and keyword parameters mixed

Position parameter is placed in front of the keyword parameter, otherwise error

s = "Hello {first}, hello{0}". Format (Python, first= "World") print (s)

Result: "Hello World, Hello Python"

5, "!a" (using ASCII ()), "!s" (using str ()), "!r" (using Repr ()) can be converted before formatting the corresponding values.

in [+]: Contents = "eels" in []: Print ("My hovercraft was full if {}.".) Format (contents)) My hovercraft is full if eels. In [All]: print ("My hovercraft is full if {!r}."). Format (contents)) My hovercraft is full if ' eels '. in [+]: print ("My hovercraft is full if {!s}.". Format (contents)) My hovercraft is full if eels. in [+]: print ("My hovercraft is full if {!a}.". Format (contents)) My hovercraft is full if ' eels '.

6, after the field can be used ":" and format instructions, better control format.

(1), the next code to approximate π to 3 digits after the decimal point

Import Mathprint ("The value of PI is approximately {0:.3f}.") Format (MATH.PI))

Results: 3.142

(2), ":" followed by an integer to limit the minimum width of the field

Table = {' Sjoerd ': 4127, ' Jack ': 4098, ' dcab ': 7678}for name, phone in Table.items ():     print (' {0:10} ==> {1:10d} '. fo Rmat (name, phone))

Results:

Jack       ==>       4098Dcab       ==>       7678Sjoerd     ==>       4127

Summarize:

% formatted as Python built-in operator, commonly used for this article mentioned in these, there are some other, such as binary related, want to know can find other information. Format uses Python's built-in functions, and there are many more uses for format, such as formatting, precision determination, padding and alignment, and so on.

Python string format output%d,%s and Format function