Detailed explanation of python conditional statement and while loop example code

02 Conditional Statements and while Loop

3-mesh operation

a = 6
# Original judgment sentence 
if a > 5:
	print(True)
else:
	print(False)
#3 Purpose operation 
print(True if a >5 else False)

Logical operation

1. 3 logical operations

And logic and

True on both sides is true

Or logic or

If one side is true, it is true

Non-logical

not logic value is inverted

Priority: not > and > or

2. Logical short circuit

# and  Logical short circuit 
a = 3 # No, right b Assignment, but the program will not report errors and can run normally 
# The left Boolean value is false, and the true or false of the right Boolean value does not affect the whole Boolean value to be false 
print(a > 4 and b > 4) # The output Boolean value is False

# or  Logical short circuit 
a = 3 # No, right b Assignment, but the program will not report errors and can run normally 
# The left Boolean value is true, and the true or false of the right Boolean value does not affect the overall Boolean value to be true 
print(a > 2 and b > 2) # The output Boolean value is True

# not  No logical short circuit 

3. Continuous judgment

#python The bottom layer will transform the continuous judgment into  and  Form of connection 
print(1 > 2 > 3) # Equivalent to  1>2 and 2>3,  Its value is False

# Logical short circuit of continuous judgment 
# Due to and There is a logic short circuit, so there is also a logic short circuit in continuous judgment 
# Integer 2 And string '3' Different types can't compare sizes 
# Left side 1>2 The Boolean value is false, so there is no need to judge on the right side, so no error will be reported 
print(1 > 2 > '3') # The output Boolean value is False

while cycle

# The loop condition can be True , but there must be internal break Ensure that the loop can be terminated, otherwise it will fall into an infinite loop 
# Use break The terminated loop is an abnormal ending loop and will not be executed else Part 
a = 1
while True:
	if a % 5 == 0:
		break
	print(a)
	a += 1
else:
	print(' End of loop ')

Exercise

Using while to write 99 multiplication table

# Use continue The terminated loop is not an abnormal ending loop, and will be executed after the loop ends else Part 
a = 1
while a < 4:
	if a % 2 == 0:
		a += 1
		continue
	print(a)
	a += 1
else: 
	print(' End of loop ')

Use random randint method to write a small game to guess numbers

i = 1
while i < 10:
	j = 1
	while j <= i:
		result = '%-3d'%(i*j)
		print(f'{j} × {i}={result}', end='')
		j += 1
	print('\n')
	i += 1

print('1 ~ 100 Guess the number game within integers, total 7 A chance! ')
import random
Min = 1
Max = 100
mynumber = random.randint(Min, Max)
i = 1
while i <= 7:
	yournumber = int(input(' Please enter the number you guessed: '))
	if yournumber == mynumber:
		print(' Congratulations, you guessed it! You are so clever! ')
		break
	elif yournumber > mynumber:
		Max = yournumber
		print(f' Your guess is too big, in {Min}~{Max} Between oh! You still have {7-i} Chance! ')
		i += 1
	else:
		Min = yournumber
		print(f' Your guess is too small, in {Min}~{Max} Between oh! You still have {7-i} Chance! ')
		i += 1
else:
	print(' Opportunities have run out! It's a pity that you didn't guess right! ')