Python Statements and syntax

Python Statements and syntax

Python Program Structure:

1. The program is composed of modules.

2. The module contains statements.

3. The statement contains an expression.

4. The expression establishes and processes the object.

Python's syntax is essentially composed of statements and expressions. The expression handles the object and is nested within the statement. Statement is also where the object is generated (for example, an expression in an assignment statement), some statements completely generate new object types (functions, classes, and so on). Statements are always present in modules, and the modules themselves are managed by statements.

Python statement:

Statement	Role	Example
Assign value	Creating reference values	A,b,c = ' good ', ' bad ', ' ugly '
Call	Execute function	Log.write (' Hello,world ')
Print Call	Print objects	Print ("Hello World")
If/elif/else	Select action	If ' print ' in Text:print (text)
For/else	Sequence iterations	For x in Mylist:print (x)
While/else	General circulation	While X>y:print ("Hello")
Pass	Empty placeholder	While True:pass
Break	Loop exit	While True: If Exittest (): Break
Continue	Continue the next cycle	While True: If Skiptest (): Continue
Def	Functions and methods	def f (a,b,c=1,*d): Print (A+b+c+d[0])
Return	function returns the result	def f (a,b,c=1,*d): return a+b+c+d[0]
Yield	Builder expression	Def gen (n): For i in N:yield i * 2
Global	namespaces, global variables	x = ' old ' def function (x): Global x,y,;x = ' new '
Nonlocal	Local Variables (python3.0+)	def outer (): x = ' old ' def function (): nonlocalx;n= ' new '
Import	Module access, importing	Import Sys
From	Module Property Access	From sys import stdin
Class	Creating objects	Class Subclass (Superclass): Staticdata = [] Def method (self): Pass
Try/except/finally	Catching exceptions	Try Action () Except Print (' Action error ')
Raise	Triggering an exception	Raise Ebdsearch (location)
Assert	Debug check	Assert x>y, ' x too small '
With/as	Environment Manager	With open (' data ') as MyFile: Process (myfile)
Del	Delete Reference	Del Data[k] Del Data[i:j] Del obj.attr Del variable

Terminating a line is the terminating statement

x = 1;

In Python, the general principle is that the end of a line automatically terminates the statement that appears on that line. That is, you can omit the semicolon.

x = 1

• The end of a line is to terminate the line statement (no semicolon).
• A nested statement is a block of code and is related to the actual indentation (without curly braces).

Although the statement is generally one line, it is possible in Python that a line is squeezed into multiple statements, separated by semicolons:

>>> a = 1;b = 2; Print (A + b)3

This is the only place in Python where a semicolon is required--as a statement delimiter.

Another special rule of a statement is that the range of a statement can span multiple lines. In order to do this, you only need to enclose the statement in parentheses (), square brackets [], or the curly braces {} of the dictionary. Any program code enclosed in these symbols can span several lines. Statement will run until it encounters a row that contains a closed parenthesis.

>>> mylist = [111222333444]>>> mylist[111, 222, 333, 444]

Parentheses can contain everything-because any expression can be included.

x = (a  + b  +    c   + d  )ifand and     = = 3)    :      Print ('helloWorld')

There is an old rule that also allows us to span several lines-when the previous line ends with a backslash, you can continue on the following line:

X = A + B +     + D

Indent in

The Python compound statement is styled in indented code. typically 4 spaces.

 while (x > 0):     ---1----    ---2----...    .

Assignment statements \ Expressions and printing

Python Statements and syntax