1. Summary Conditional: if .. else New Nested conditional elif
Repetition -- while

2. Pictorial view of how if works
if (expression):
true
false
next indented block
else: Statements

3. Grades Suppose we have a letter-grade system: 0<= grade <=50 – D
Perfectly fine with
0<= grade <=50 – D
50 <grade <=70 – C
70 <grade <=90 – B
90 <grade <=100 –A
if 0<= grade <=50: letterGrade =‘D’
if 50 <grade <=70: letterGrade =‘C’
if 70 <grade <=90 : letterGrade =‘B’
if 90 <grade <=100 : letterGrade =‘A’
print(‘The letter grade is ‘ +letterGrade)

4. Multi-way branches Conditions are mutually exclusive
if 0<= grade <=50:
letterGrade =‘D’
else:
print(‘The letter grade is ‘ +letterGrade)
if grade <=70:
letterGrade =‘C’
else:
if grade <=90:
letterGrade =‘B’
else:
letterGrade =‘A’

5. Multi-way branches with elif
if 0<= grade <=50:
letterGrade =‘D’
elif grade <=70:
letterGrade =‘C’
elif grade <=90:
letterGrade =‘B’
else:
letterGrade =‘A’
print(‘The letter grade is ‘ +letterGrade)
if 0<= grade <=50:
letterGrade =‘D’
else:
if grade <=70:
letterGrade =‘C’
if grade <=90:
letterGrade =‘B’
letterGrade =‘A’
print(‘The letter grade is ‘ +letterGrade)

6. Another Multi-way Branches
if 0<= grade <=70:
if grade <=50:
letterGrade =‘D’
else:
letterGrade =‘C’
if grade <=90:
letterGrade =‘B’
letterGrade =‘A’
print(‘The letter grade is ‘ +letterGrade)
if 0<= grade <=50:
letterGrade =‘D’
else:
if grade <=70:
letterGrade =‘C’
if grade <=90:
letterGrade =‘B’
letterGrade =‘A’
print(‘The letter grade is ‘ +letterGrade)

7. While if vs. while count=0 if count< 5: print(“Hello!’)
count= count+1
count=0
while count< 5:
print(“Hello!’)
count= count+1

8. How if & while works While (expression): if (expression): True True
False
False
Statements
Statements

9. Guess a number in 5 times
Within 5 trials, guess the name ‘kim’ and quit if correct
count=0
while count< 5:
name=input(‘Enter a name.’)
if name==‘kim’: count=5
count= count+1
count=0
while count< 5:
print(“Hello!’)
count= count+1

10. Guess a number in 5 times Within 5 trials, guess the name ‘kim’
count=0
while count< 5:
name=input(‘Enter a name.’)
if name==‘kim’:
break
count= count+1
count=0
while count< 5:
name=input(‘Enter a name.’)
if name==‘kim’:
count=5
count= count+1

11. Guess name and password
Within 5 trials, guess the name ‘kim’ and password
def logIn():
count=0
while count < 5:
count= count+1
name=input(‘Enter a name.’)
if name !=‘kim’:
continue
passwd = input(‘What is password?’)
if passwd == ‘xxx’:
break
if count < 5:
print(‘Access granted’)
else:
print(‘Five attempts failed.’)

12. HW 2-- Guessing game (Due 9/21)
A random number between 1 and 10 is obtained from
import random
randNum = random.randint(0,10)
Write a function guess(), which generates a random integer between 1 and 9 (inclusive) and let a user enter a number up through five times to match the random number
your working Python file (guess.py) to
def guess():
import random
randNum = random.randint(0,10) .