Is it possible to distinguish binary predicates from unary ones, and what are the main differences between them?

Unary and binary predicates are functions or functional objects that return a boolean value but differ in the number of arguments:

• Unary predicate takes one argument and returns true or false depending on the condition, for example, checking if a number is even.
• Binary predicate takes two arguments and compares them, returning true or false, for example, comparing two numbers for equality or less than.

They can be distinguished by their function signature:

// Unary predicate
bool isEven(int x);

// Binary predicate
bool less(int a, int b);

Both types of predicates are often used in STL templates and algorithms: unary predicates for filtering elements, binary predicates for comparison and sorting. The main difference is the number of parameters and the purpose of the check.