What is an Expression?
An expression is a combination of symbols, variables, constants, operators, and functions that evaluate to a value or result.
You can think of expressions as mathematical statements - they take in one or more pieces of data (variables or constants) and perform operations on them to compute some kind of output.
For example, the expression 2 + 3 evaluates to 5. The two numbers in this expression are called operands while the operator + performs the addition operation.
Some other common operators are subtraction (-), multiplication (*), division (/), and modulus (%, which returns the remainder after division).
So in essence, an expression is like a tiny computer program - it takes in input and performs some kind of computation on it to produce an output.
Different Types of Expressions
Expressions come in many shapes and sizes.
Some are simple like x + 2. Others can involve more complicated operations such as function calls with multiple parameters: Math.max(x1, x2).
Generally speaking, there are three main types of expressions: arithmetic expressions, logical expressions, and functional expressions.
Arithmetic Expressions
Arithmetic expressions are used to perform calculations involving numbers using basic math operators such as addition (+), subtraction (-), multiplication (*), division (/) and others.
They usually include two operands (e.g., 5 + 2) but could also include multiple operands in certain cases (e.g., 5 + 2 + 8). The result of evaluating an arithmetic expression typically depends upon the values held by its operands as well as their corresponding operator type (i.e., addition vs multiplication).
Logical Expressions
Logical expressions involve comparison operators such as equal-to (==), not-equal-to (!=), greater-than (>=), less-than (<=), and others.
These operators allow you compare two values stored within variables or constants for truthiness - that is if they represent true or false statements based on particular conditions set by your program's logic flow/structure.
For example, you might write a conditional statement like: if x >= y then do something, which would only activite if "x" is indeed greater than or equal to "y".
Functional Expressions
Functional expressions employ functions - pieces of code that take arguments from caller functions/procedures and return a value based on those arguments' values combined with other built-in logic present within the function body itself.
Common examples include:
- string manipulation functions such as substr() and trim()
- math functions such as min() and max()
- looping structures such as foreach() , map() and filter().
Each of these has its own purpose depending upon what you're trying to accomplish with your program/application's end goal in mind