Python / Conditions

PYTHON PROGRAMMING · 12 MIN READ

Conditions and Boolean expressions

A Boolean expression is either true or false; an if statement uses that result to select a block.

Learning objectives

  • Write an if/elif/else chain.
  • Trace which branch runs for an input.

Choose one path

PYTHON
marks = 72
if marks >= 90:
    result = "excellent"
elif marks >= 40:
    result = "pass"
else:
    result = "try again"

For 72, the first test is false and the second is true, so result becomes "pass". Later branches are skipped once a true condition is found.

Common mistakes

  • Use == to compare values; = is assignment.
  • Order overlapping tests from the most restrictive condition to the broadest one.
  • Indent each suite consistently.

References