3 plus symbols between two variables (like a+++b) in C [duplicate]

I like the explanation from Expert C Programming:

The ANSI standard specifies a convention that has come to be known as the maximal munch strategy. Maximal munch says that if there's more than one possibility for the next token, the compiler will prefer to bite off the one involving the longest sequence of characters. So the example will be parsed

c = a++ + b;

Read Maximum Munch Principle

"maximal munch" or "longest match" is the principle that when creating some construct, as much of the available input as possible should be consumed.

Every compiler has a tokenizer, which is a component that parses a source file into distinct tokens (keywords, operators, identifiers etc.). One of the tokenizer's rules is called "maximal munch", which says that the tokenizer should keep reading characters from the source file until adding one more character causes the current token to stop making sense