original file
this is unedited

relational operators

• compared the values of the two operands
• relational expression: two operands and one relational operator
• the value of an expression is often Boolean except when Boolean is not a type in the lang

Examples of inequality operator: != (C-based), ~= (Lua), .NE or <> (Fortran), <> ML and F#, === and !== (JavaScript, PHP to prevent coercion of the operands)

• Relational operators have lower precedence than arithmetic operators so for the expression a + 1 > 2 * b the arithmetic expressions will be evaluated first.

boolean expressions

• boolean variables, boolean constants, boolean operators, and relational expressions
• operators: AND OR NOT sometimes OR XOR
  • usually take only boolean operands and produce boolean variables
• Arithmetic expressions can be the operands on relational expressions and relational expressions can be the operands of Boolean expressions, so they must be placed in different precedence levels.

For C-based languages (those prior to C99 had no boolean type and value so 0 was false and non-zero was true.)

//try running
int main()  
{  
 int a = 3;  
 int b = 2;  
 int c = 1;  
  
 int x = a > b > c;  
 printf("%d",x);  
}

• The leftmost operator is evaluated first because in C relational operators are left associative, so a will be compared to b the result of which could either be 1 or 0. Afterwards, this result is compared with c. Note that the value of b is never compared to c.

//try running
public static void main(String[] args) {
   int a = 1;
   int b = 2;
   int c = 3;
   System.out.println(a > b > c);
}

// "would output bad operand types for binary operator"