python--syntax

Python Syntax

Judgment statement

if An expression

if An expression :

Statement 1

else :

Statement 2

If ... elif elif ... Else .....

State1 if expression else State2 ( Implementation of the three-mesh operator )

A If a > b else b

The statement is a judgment of if, and if a>b, returns the value of A; if a<=b , the value of b is returned .

Looping statements

While expression : A statement that satisfies the execution of an expression

State1

While expression : A statement that satisfies the execution of an expression

State1

Else

State2

dead loop / Infinite loop

While True:

print "Hello"

when the value of count is less than 1, when the value of count is greater than ten when launched directly

Count = 1,5,10,15

While Count < 10:

Print Count

Count + = 1

Exit ()

Circular statement Type user keyword

Break: jump out of a loop, no longer looping statements

Continue: jump out of this cycle, continue to return to the Loop statement, the next loop ;

Pass: Skip this procedure and proceed to the next procedure;

syntax for the FOR loop in python :

for I in an iterative object:

State1 ....

Range

range () is a set of numbers tool, basic structure: Span style= "Font-family:calibri" >range (start,stop,step) , from start start, Stop end, not including stop this number, step start can be omitted, default to 0 stop step 1

For, while,else,elif,if, Application of statements such as if not

1, the server host information input

2, the input of the command

1)cmd = display command line prompt, wait for user input;

2) If the command is empty, jump out of this cycle, continue to receive user commands;

3) If the command is quit, jump out of all loops and end the program ;

4) If there is a command, print "Run%s"% (cmd)

Research points :

a). dead Loop while statement;

b). The nesting of the Loop statement and the if statement ;

c). the difference between break and continue ;

3, write 99 multiplication table :

1*1=1

1*2=2 2*2=4

1*3=3 2*3=6 3*3=9

........

1*9=9 ......... .......... 9*9=81

Research points :

nesting for loops

range uses

4, the user input string , Print the string after the reversal ;

1) Whether the variable name is legal judgment procedure ;

2) variable name naming rules : consists of letters, underscores, or numbers, but cannot start with numbers ;

Reference point:

s = "Hello"

Please enter a variable name :

1>. determines whether the first character is composed of a letter or an underscore ;

2>. if the first word conforms to the law, determine whether the remaining characters are composed of letters, numbers, or underscores ;

5. Enter two strings, remove all ego from the second string from the first string. For example, enter "They is students." " and " Aeiou ", the first string after deletion becomes " Thy R stdnts. "

input: Each test input contains 2 characters

Output: Output the deleted string

Example:

Input

They is students.

Aeiou

Output

Thy R stdnts.

Reference point:

1) traverse str1;

2) determines whether the str1 character is a member of the str2 ( substring );

3) If it is a member, replace the character with an empty one to achieve the purpose of the deletion ;

python--syntax