Knowledge required by Python testers

Knowledge required by Python testers

A. String definition method

Use single quotes (')

You can use single quotes to indicate strings, just like 'quote me on this. All spaces, that is, spaces and tabs are retained as they are.

Double quotation marks (")

The strings in double quotes are exactly the same as those in single quotes. For example, "What's your name? ".

Use three quotation marks (''' or """)

You can use three quotation marks to indicate a multi-line string. You can use single quotes and double quotes freely in three quotes. For example:

'''This is a multi-line string. This is the first line.This is the second line."What's your name?," I asked.He said "Bond, James Bond."'''

Escape Character

Use \ 'to indicate single quotes -- pay attention to this backslash. Now you can represent the string as 'What \'s your name? '.

The method to indicate this special string is "What's your name? ", That is, double quotation marks or three quotation marks.

In a string, a separate backslash at the end of the line indicates that the string continues in the next line, rather than starting a new line. For example:

"This is the first sentence.\This is the second sentence."

B. Variables

The method for defining variables is similar to that of other languages. variable types are determined by assigning values.

Int type Number = 0 String type String = ''Dict type dict = {}

C. indent

Statements at the same level must have the same indentation. Each group of such statements is called a block

i = 5 print 'Value is', iprint 'I repeat, the value is', i

D. Operators

Operator	Name	Description	Example
+	Add	Add two objects	3 + 5 get 8. 'A' + 'B' get 'AB '.
-	Subtraction	Returns a negative number or a number minus another number.	-5.2 returns a negative number. 50-24 get 26.
*	Multiplication	Returns a string that is repeated several times.	2*3 get 6. 'La '* 3 to get 'lala '.
/	Division	X divided by y	4/3 to get 1 (integer division to get the integer result ). 4.0/3 or 4/3. 0 get 1.3333333333333333
//	Integer Division	Returns the integer part of the operator.	4 // 3.0 get 1.0
%	Modulo	Returns the remainder of the Division.	8% 3 get 2. -25.5% 2.25 get 1.5
<	Less	Returns whether x is less than y. All comparison operators return 1 to indicate true, and 0 to indicate false. This is equivalent to the special variables True and False. Note: These variable names are capitalized.	5 <3 returns 0 (False) and 3 <5 returns 1 (True ). Comparison can be connected at any time: 3 <5 <7 returns True.
>	Greater	Returns whether x is greater than y.	5> 3 return True. If both operands are numbers, they are first converted to a common type. Otherwise, it always returns False.
<=	Less than or equal	Returns whether x is less than or equal to y.	X = 3; y = 6; x <= y returns True.
> =	Greater than or equal	Returns whether x is greater than or equal to y.	X = 4; y = 3; x> = y returns True.
=	Equal	Equal comparison object	X = 2; y = 2; x = y returns True. X = 'str'; y = 'str'; x = y, False is returned. X = 'str'; y = 'str'; x = y returns True.
! =	Not equal	Compare whether two objects are not equal	X = 2; y = 3; x! = Y returns True.
Not	Boolean "Non"	If x is True, False is returned. Returns True if x is False.	X = True; not y returns False.
And	Boolean "and"	If x is False, x and y returns False. Otherwise, it returns the calculated value of y.	X = False; y = True; x and y, returns False because x is False. Python does not calculate y here, because it knows that the value of this expression must be False (because x is False ). This phenomenon is called short circuit computation.
Or	Boolean "or"	If x is True, it returns True; otherwise, it returns the calculated value of y.	X = True; y = False; x or y returns True. Short circuit calculation is also applicable here.

The most common ones are small (equal) at, large (equal) at, (not) equal to, not, and, or

E. Control Flow

If statement

number = 23guess = int(raw_input('Enter an integer : ')) if guess == number:  print 'Congratulations, you guessed it.' # New block starts here  print "(but you do not win any prizes!)" # New block ends hereelif guess < number:  print 'No, it is a little higher than that' # Another block  # You can do whatever you want in a block ...else:  print 'No, it is a little lower than that'  # you must have guess > number to reach here print 'Done'# This last statement is always executed, after the if statement is executed if 'a' in name:  print 'Yes, it contains the string "a"'

The elif and else sections are optional.

While statement

number = 23running = Truewhile running:  guess = int(raw_input('Enter an integer : '))  if guess == number:    print 'Congratulations, you guessed it.'    running = False # this causes the while loop to stop  elif guess < number:    print 'No, it is a little higher than that'  else:    print 'No, it is a little lower than that'else:  print 'The while loop is over.'  # Do anything else you want to do hereprint 'Done'

For statement

For I in range (1, 5): print I is equivalent to for I in range (5): print I

For Loop recursion in this range -- for I in range () is equivalent to for I in [1, 2, 3, 4], this is like assigning each number (or object) in the sequence to I, one at a time, and then executing the program block with each I value

Break statement

while True:  s = raw_input('Enter something : ')  if s == 'quit':    break  print 'Length of the string is', len(s)print 'Done'

Continue statement

while True:  s = raw_input('Enter something : ')  if s == 'quit':    break  if len(s) < 3:    continueprint 'Input is of sufficient length'