Relational and Logical Operators

Boolean expressions combine relational operators (comparing values) with logical operators (combining conditions). They evaluate to true or false.

x = 7
print(x > 5)               # True
print(x == 10)             # False
print(x > 5 and x < 10)    # True
print(x < 5 or x > 6)      # True
print(not x == 7)          # False

x <- 7
DISPLAY(x > 5)             {true}
DISPLAY(x = 10)            {false}
DISPLAY(x>5 AND x<10)      {true}
DISPLAY(x<5 OR x>6)        {true}
DISPLAY(NOT(x = 7))        {false}

Truth Table Rules

AND: true only when BOTH sides are true.
OR: true when AT LEAST ONE side is true.
NOT: flips the value.

Exam trap: OR is inclusive. true OR true = true. Students sometimes assume it means “either/or but not both.” It doesn’t.

Practice Problems