A comparison evaluates a relationship between values and produces a Boolean result: True or False. Python uses symbols such as >, <, >=, <=, ==, and != to compare values. section 4.3.3
Use comparisons to control decisions and check boundaries:
- Place a comparison in an if statement to choose which code runs; else is optional. section 4.3.3
- Combine comparisons with and when a value must satisfy multiple conditions, such as being within a range. section 8.3.4
- Choose > and < for an exclusive range, or >= and <= when the boundary values count. section 8.3.4
- Write == to test equality; a single = is not the equality comparison shown here. section 4.3.3
Selecting values between two bounds
A function can count values strictly between x and y with `if number > x and number < y:`. Changing the conditions to `>=` and `<=` includes the endpoints. Testing a list from 1 through 9 with bounds 3 and 7 exposes the difference: inclusive comparisons count 5 values, while exclusive comparisons count 3. section 8.3.4
Listing 4.2 Function to determine the larger of two values
def larger(num1, num2):
if num1 > num2: #1
return num1 #2
else: #3
return num2 #4
Inspect a small function that compares two values and returns the larger one. section 4.3.3
