First, the basic structure of the program
Program flow chart
Second, a simple branch
1、if<condition>:<body>
else:<body>
2, relational operators: <, <=, ==,> =,>, =!
3 Examples
## Solving quadratic
Import Math
DEF main ():
A, B, C = the eval (INPUT ( 'Enter equation three parameters (A, B, C):'))
Delta. 4-B * = B * C * a
IF a == 0:
X = -b / C
Print ( '\ n-not a quadratic equation of the equation, only one solution is:', X)
elif Delta <0:
Print ( 'without the quadratic equation real root! ')
elif Delta == 0:
discRoot Math.sqrt = (Delta) ## square root
the root1 = (-b + discRoot) / (2 * a)
Print (' \ n-root of the equation only as a weight: ', the root1)
the else:
discRoot Math.sqrt = (Delta) ## square root
the root1 = (-b + discRoot) / (2 * A)
root2 = (-b - discRoot) / (2 * A)
Print (' \ n two real roots of the equation are: ', the root1, root2)
main ()
Third, the exception handling
1、try.......except......
True the while:
the try:
the X-= int (the INPUT ( 'Please enter a number:'))
BREAK
the except Va lueError:
Print ( '! not a valid digital input enter again!')
2、try......except........else......finally.....
there is an abnormality try to perform except, without exception executed else, regardless of whether an exception occurs finally have to perform
main DEF ():
the try:
num1, num2 = the eval (INPUT ( 'Enter two digits do division, Comma Separated:'))
Result = num1 / num2
the except the ZeroDivisionError:
Print ( '0 divisor can not do!')
SyntaxError the except:
Print ( '! least enter a comma')
the except:
Print ( 'input error!')
the else:
Print ( 'no error, the calculation result is:', result)
the finally:
Print ( 'last statement executed .. . ')
main ()
## Solving quadratic
Import Math
DEF main ():
: the try
( 'Enter. 3 equation parameters (A, B, C):' INPUT ()) A, B, C = the eval
Delta B * = B- A * C *. 4
discRoot Math.sqrt = (Delta) ## square root
the root1 = (-b + discRoot) / (2 * A)
root2 = (-b - discRoot) / (2 * A)
Print ( '\ n two real roots of the equation are: ', the root1, root2)
the except a ValueError aS excObj:
IF STR (excObj) ==' Math Domain error ':
! Print (' no real roots ')
the else:
Print (' no to correct the coefficient ')
the except NameError:
! Print (' not three digital inputs')
the except TypeError:
Print ( 'the digital input is not')
the except SyntaxError:
print ( 'input in the form of error, may not enter a comma-separated'))
except:
print ( 'Other types of errors')
main ()
Examples ---- find out the three largest
The maximum number of ## N
: DEF main ()
( 'the number of input values:' INPUT ()) the eval = n-
max = the eval (INPUT ( 'input first number >>>>'))
for I Range in (n--. 1):
X = the eval (iNPUT ( 'enter the next number >>>>'))
IF X> = max:
max = X
Print ( 'maximum value is:', max)
main ()
# # max () function of
x, y, z = eval ( input ( ' enter number 3:'))
Print ( 'maximum value is:', max (x, y , z))
Fourth, the loop structure
1, for loop
The need to provide a fixed number of cycles
Each element in the list loop ##
words = [ 'Hello', 'Sleeping', 'tommorrow']
for words in W:
Print (W, len (W))
2, while circulation
continue --- terminate this cycle
break ----- terminate the entire cycle
Loop statement else
in n-Range for (2,10):
for X in Range (2, n-):
IF% n-X == 0:
Print (n-, '=', X, '*', X n-//)
BREAK
the else:
print (n, 'is a prime number')