If Statements¶

if statements have this general form:

if conditional :

body

and

if-else statements have this general form:

if conditional :

if-body

else:

else-body

and

if-elif-else statements have this general form:

if conditional :

if-body

elif conditional :

elif-body

else:

else-body

Write an if statement that executes the body only if v1 is less than v2. The body should simply contain print('yes'). # replace this comment with your if statement print('yes') ====

Look at the top of this file for a reminder about the formatting of an if statement.

You do not need an else part.

if v1 < v2: print('yes')

Write an if statement that prints yes if v1 is greater than v2 and prints no otherwise. # replace this comment with your code ====

Look at the top of this file for a reminder about the formatting of an if-else statement.

You need an else part.

if v1 > v2: print('yes') else: print('no')

Write an if statement that prints yes if v1 is less than v2 and v3 is equal to v4. Nothing is printed otherwise. # replace this comment with your if statement ====

Use and to join the two boolean expressions.

You do not need an else part.

Don’t forget to use ==, not = (which is assignment).

if v1 < v2 and v3 == v4: print('yes')

If v1 = 1, and v2 = 2, create string variable resStr which refers to variable 1 is 1 (1.0) and variable 2 is 2 (2.0). # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(resStr, 'variable 1 is 1 (1.0) and variable 2 is 2 (2.0)') myTests().main()

To make sure you have only 1 digit after the decimal, use this format specifier: %.1f

You can use a variable multiple times in the same tuple.

resStr = 'variable 1 is %d (%.1f) and variable 2 is %d (%.1f)' % (v1, v1, v2, v2)

Write an if statement that prints is not 3 times if v1 is not equal to 3 times the value of v4. # replace this comment with your code ====

To make sure you have only 1 digit after the decimal, use this format specifier: %.1f

Not equal to is !=.

if v1 != 3 * v4: print('is not 3 times')

Write an if statement that assigns res to ‘even number’ if variable idx is an even number and res to ‘odd number’ otherwise. # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(res, 'odd number') myTests().main()

You can tell if a value is even if when you divide it by 2, the remainder is 0.

if idx % 2 == 0: res = 'even number' else: res = 'odd number'

Write an if statement that assigns res to 1 if variable v1 is strictly between 100 and 200. # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(res, 1) myTests().main()

Use < and > and and.

Remember that you have to have a value, variable, or expression on each side of a < or >. You cannot write v1 > 100 and < 200 because there is no expression on the left side of the <.

if v1 > 100 and v1 < 200: res = 1 # could also write: if 100 < v1 < 200:

Write an if statement that assigns leap to True if variable year is a multiple of 4 and is not a multiple of 100, and to False otherwise. # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(leap, False) myTests().main()

A number n is a multiple of another number d, if when you divide n by d, the remainder is 0.

if year % 4 == 0 and year % 100 != 0: leap = True else: leap = False

Write an if statement that assigns 1 to answer if variable result has the value 100, and sets answer to 2 otherwise. # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(answer, 2) myTests().main()

Use an if-else statement.

if result == 100: answer = 1 else: answer = 2

Write an ifelse statement that sets the value of a variable gradepoint to 4 if a variable score is greater than 90, 3 if score is between 80 and 89, 2 if score is between 70 and 79, 1 if score is between 60 and 69, and 0 otherwise. # replace this comment with your code ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(gradepoint, 2) myTests().main()

Use an if-elif-else statement.

if score > 90: gradepoint = 4 elif score > 80: gradepoint = 3 elif score > 70: gradepoint = 2 elif score > 60: gradepoint = 1 else: gradepoint = 0

Write a short program that first asks the user to input 3 numbers. (Do this with 3 individual input() calls, storing the results in 3 variables.) Then, the program prints out the largest of the 3 numbers. You may assume the user enters three distinct values. # replace this comment with your code ====

Use multiple if/elif statements, each with multiple boolean operators connected together with and s.

v1 = float(input("Enter first value:")) v2 = float(input("Enter second value:")) v3 = float(input("Enter third value:")) if v1 > v2 and v1 > v3: print(v1) elif v2 > v1 and v2 > v3: print(v2) else: print(v3)

Write a short program that asks the user for a payrate and a number of hours, and then prints out the total pay. Any hours over 40 are paid with time and a half. # replace this comment with your code ====

Use an if-else statement.

payrate = float(input("Enter hourly payrate: ")) hours = float(input("Enter total hours worked: ")) if hours > 40: pay = payrate * 1.5 * (hours - 40) + payrate * 40 else: pay = payrate * hours print('Your pay will is', pay)

On a roulette wheel, the pockets are numbered from 0 to 36. The colors of the pockets are as follows:
- Pocket 0 is green.
- For pockets 1 through 10, the odd-numbered pockets are red and the even-numbered pockets are black.
- For pockets 11 through 18, the odd-numbered pockets are black and the even-numbered pockets are red.
- For pockets 19 through 28, the odd-numbered pockets are red and the even-numbered pockets are black.
- For pockets 29 through 36, the odd-numbered pockets are black and the even-numbered pockets are red.
Write a program that asks the user to enter a pocket number and displays whether the pocket is green, red, or black. The program should display an error message if the user enters a number that is outside the range of 0 through 36.
# replace this comment with your code ====
Use an if-elif-else statement with nested if statements in each part. An odd number is one where when you divide by 2, the remainder is 1.

pocket = int(input("Enter a pocket number from 0 to 36, inclusive: ")) if pocket < 0 or pocket > 36: print("That is not a legal pocket number.") elif pocket == 0: print("Pocket is green") elif pocket >= 1 and pocket <= 10: if pocket % 2 == 1: print("Pocket is red") else: print("Pocket is black") elif pocket >= 11 and pocket <= 18: if pocket % 2 == 0: print("Pocket is red") else: print("Pocket is black") elif pocket >= 19 and pocket <= 28: if pocket % 2 == 1: print("Pocket is red") else: print("Pocket is black") else: if pocket % 2 == 0: print("Pocket is red") else: print("Pocket is black")

Write a program that asks the user to enter two numbers and an operator to apply to them. The operator must be one of +, -, *, /, //, or %. The program applies the operator to the numbers and prints the result.

Here is an example run:

Enter first number: 46

Enter second number: 13.5

Enter an operator (one of +, -, *, /, //, %): -

46.0000000 - 13.5000000 = 32.500000

If the user enters an illegal operator, the program prints an error message.
# replace this comment with your code ====

Use an if-elif-else statement. The print statement for the + operator looks like this:

print('%f + %f = %f' % (num1, num2, num1 + num2))

num1 = float(input("Enter first number: ")) num2 = float(input("Enter second number: ")) op = input("Enter an operator (one of +, -, *, /, //, %): ") if op == '+': print('%f + %f = %f' % (num1, num2, num1 + num2)) elif op == '-': print('%f - %f = %f' % (num1, num2, num1 - num2)) elif op == '*': print('%f * %f = %f' % (num1, num2, num1 * num2)) elif op == '/': print('%f / %f = %f' % (num1, num2, num1 / num2)) elif op == '//': print('%f // %f = %f' % (num1, num2, num1 // num2)) elif op == '%': print('%f % %f = %f' % (num1, num2, num1 % num2)) else: print('%s is an unknown operator' % op)