2.5. Operators and operands

Operators are special symbols that represent computations like addition and multiplication. The values the operator is applied to are called operands.

The operators +, -, *, /, and ** perform addition, subtraction, multiplication, division, and exponentiation, as in the following examples:

print(20+32) print(75-1) print(5**2) print((5+9)*(15-7))

There was a change in the division operator between Python 2.x and Python 3.x. In Python 3.x, the result of this division is a floating point result:

minute = 59 print(minute/60)

The division operator in Python 2.0 would divide two integers and truncate the result to an integer:

>>> minute = 59
>>> minute/60
0

To obtain the same answer in Python 3.0 use floored ( // integer) division.

minute = 59 print(minute//60)

In Python 3.0 integer division functions much more as you would expect if you entered the expression on a calculator.

csp-10-2-4: What is the result of 3 / 4?

• 0
• If the two values are both integers (whole numbers) you will normally get an integer (whole number) result in older Python environments. But, this book is using Python 3 so you get a decimal result.
• 1
• This would be correct if the result was rounded up before the values after the decimal point were thrown away, but it does not do this.
• 0.75
• While this isn't the what older Pyton development environments would return, in this book we are using Python 3 so it returns a decimal result.
• 0.25
• This would be correct if it was 1 / 4, 1.0 / 4, or 1 / 4.0

csp-10-2-5: What operator (symbol) would you use to truncate division in Python 3.0?

csp-10-2-6: Match each expression with the operation it performs. Try assigning values to these variables and testing out the espressions in your python interpreter.
• x + y
• addition
• x - y
• subtraction
• x * y
• multiplication
• x / y
• division
• x % y
• remainder (modulus)
• x // y
• floored division
• x ** y
• exponentiation

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