C++ :: Plus Or Minus Notation

Is there a simple notation to check if a value is within a plus or minus range?

E.g.
//I read a value A. delay(50); //Read value again -calling this value B delay(50);
//Read value again -calling this value C delay(50); //Read value again -calling this value D delay(50);
//Read value again -calling this value E
Check IF first value A is within 5 of the value B and within 5 of value C, etc.

I can think of a few round about ways of doing this but is there any simple "equals to plus or minus" notation? (what I actually want to do is to check a lot more values than this and it will get very complicated with any of my solutions)....