Operators
Operators are symbols that tell the compiler or an interpreter to provide specific logic operations or mathematical calculations.
Operators are tyically consistent across languages, so once you learn them in one language, the knowledge will transfer to others if you are using them on the same/equivalent types.
Arithmetic
Mostly used for math, but I see people use ‘+’ frequently with strings to combine them together.
| Sample usage | In English | Result |
|---|---|---|
| a + b | a plus b | If the types were numbers, 1 + 2 would give you 3. If they were strings, “richard” + “tester” would give you “richardtester” |
| a - b | a minus b | If the types were numbers, 5 -1 would give you 4 |
| a * b | a times b | If the types were numbers, 2 * 2 would give you 4 |
| a / b | a divide b | If the types were numbers, 8 / 2 would give you 4 |
| a % b | a mod b | It returns the remainder of the division. So 8 % 5 would give you 3 |
Logical
Mostly used in control flow to help us control the flow of our code.
| Sample usage | In English | Result |
|---|---|---|
| a & b | Evaluate all values and returns logical conjunction (AND) | If these are boolean, ‘true & false’ would return false. |
| a && b | Evaluates all values, but stops if first value returns false | So false && true would return false and not evaluate or run b. |
| a || b | Evaluates all values and returns the logical disjunction (OR) | Used in Control Flow to see if a or b is true and carry on |
| !a | Basically means NOT | This tends to only work on boolean types. !true if the expression is not true, carry on |
Relational
Used for type comparisons. A lot of this logic is what a test framework like JUnit is doing under the hood.
| Sample usage | In English | Result |
|---|---|---|
| a == b | a is equal to b | If a was “richard” and b was “richard” it would return true |
| a != b | a is not equal to b | If a was “richard” and b was “sarah” it would return true |
| a < b | a is less than b | 6 < 15 would return true |
| a > b | a is greater than b | 15 > 6 would return true |
| a <= b | a is less than or equal to b | 15 <= 15 would be true. 6 <= 15 would also return true |
| a >= b | a is greater than or equal to b | 15 >= 15 would be true. 25 >= 15 would also return true |
Assigment
| Sample usage | In English | Result |
|---|---|---|
| a = b | make a the value of b | if a was 7 and b was 10, after this code a would be assigned the value of 10 |
| new object | make a new instance of an object | If we had a class called Person, Person richard = new Person() would make a new instance of Person called richard |
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