Python notes-1

Tag: ASC Specifies bytes nal specified position pytho statistic output white

Variable naming rules:

1, can only be letters, numbers, underline any combination

2. The first character of a variable cannot be a number

3. The following keywords cannot be used as variable names:

And, as, assert, break, class, continue, Def, Del, elif, else, except, exec, finally, for , from, Global, if, import, in, is, Lambda, not, or, pass, print, raise, return, try, while, with, yield

4, general constant all uppercase letters

5. Official Recommendation: a_b_1 = variable

Computer minimum representation unit: bit binary one

Computer minimum storage unit: 8bits = 1Byte = 1 bytes

1024byte = 1KBytes 1KB 1024x768 assic character

1024KB = 1mbytes

1024mbytes = 1GB

1024GB = 1TB

Data type: (double quotation marks are double quotation marks in English)

int (integer type)

Long (integer)

Float (float type)

Complex (plural)

Boolean value (True or FALSE, True or FALSE, 1 or 0)

String: The quoted value is the string

name = "Syan yans\n" (not modifiable)

　　　　Age = 20

　　　　Remove white space: Name.strip () (remove only two blanks, the middle does not go)

　　　　 Segmentation

　　　　 Length: Len (name)

　　　　 Index: name[2]

　　　　 Slices: name[0:3] Gu Tou regardless of the tail

　　　　 Formatted output: msg = "My name is%s, I am%s"% (name, age)

　　　　 Splicing: msg = "My name is" + name (string and number cannot be spliced)

　　　　 list: name = [] Empty list

stored value: name = ["Syan", "Yans", "yans1", "Jack", "Rian"]

value: name[1]

change value: name[1] = "Bob"

added: Name.append ("Luci") ————— > Append to Last

Insert before specified position: Name.insert (1, "Sun")

Delete value: Del name[3]

name.remove ("Syan")

accurate to a value: Name.index ("Yans")

name[name.index ("Yans")] = "yans1" 　　　　　

statistics How many duplicate values: Name.count ("yans1")

sort: Name.sort () ———— > in alphabetical order by ASCII code

name.reverse () ————— > in reverse order of ASCII code

value: Name[0:4]

interval value: Name[0:-1:2] ————— > Last value refers to length (default interval 1)

Python notes-1