In this post, we will see Relational and Boolean Expressions | PPL | Sebesta | Expressions and Assignment Statements | relational and boolean expressions, ppl, sebesta, expressions and assignment statements
4. Relational and Boolean
Expressions
A relational operator is an operator that compares the
values of its two operands. A relational expression has two operands and one
relational operator.
The value of a relational
expression is Boolean.
The syntax of the relational operators for equality and
inequality differs among some programming languages. For example, for
inequality, the C-based languages use != , Ada uses /= , Lua uses ~= , Fortran
95+ uses .NE. or <> , and ML and F# use <> .
JavaScript and PHP have two additional
relational operators, === and !== . These are similar to their relatives, ==
and != , but prevent their operands from being coerced. For example, the
expression
"7" == 7
is true in JavaScript,
because when a string and a number are the operands of a relational operator,
the string is coerced to a number. However,
"7" === 7
is false, because no coercion is done on the operands of this
operator.
The relational operators always have lower
precedence than the arithmetic operators, so that in expressions such as
a + 1 > 2 * b
the arithmetic expressions
are evaluated first.
Boolean expressions consist of Boolean variables,
Boolean constants, relational expressions, and Boolean operators. The
operators usually include those for the AND, OR, and NOT operations, and
sometimes for exclusive OR and equivalence. Boolean operators usually take only
Boolean operands (Boolean variables, Boolean literals, or relational
expressions) and produce Boolean values.
The precedence of the arithmetic, relational, and
Boolean operators in the C-based languages is as follows:
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