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In this video, will learn about c++ expressions and statements.

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Let's start with expressions.

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Expressions are the most basic building blocks in programming.

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Expressions are defined as follows in the c++ standard.

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A sequence of operators and operands that specifies a computation.

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We'll see some examples shortly. But for now you can think of an expression

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as a sequence of operation operators that computer value.

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That's a pretty simplistic view, but it will

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serve us well until we learn more advanced c++ features.

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Let's see some example c++ expressions.

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Let's start with the literal 34.

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That's an expression whose value is simply 34.

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Variables, such as favorite number in this example, are also expressions

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since their value is the value of the variable.

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We can also have mathematical expressions, such as 1.5 + 2.8,

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which will add those two numbers.

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And 2 * 5, which will multiply 2 and 5.

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There are many, many more examples of expressions

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since they're many operators in c++,

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and we can combine them to make any expression we wish.

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If we wanted to test to see if A was greater than B,

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where A and B are variables, we can use the greater than sign between the A and the B.

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This evaluates to a Boolean, a true false value.

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Notice the last example, this is an assignment expression.

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We are assigning B to A.

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This is also an expression because the value of this expression is what we just assign.

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We'll talk more about this in a few videos when we talked about assignment statements in detail.

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Now let's see what makes a statement different from an expression.

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A statement is a complete line of code that performs some action.

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Statements are usually terminated with a semicolon.

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When you first learn c++,

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it's a very common error to forget to terminate statements with semicolons.

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Statements usually contain expressions.

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As you would expect, c++ has many types of statements.

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It has expression statements, the null statement, compound statements and more.

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We'll discuss specific types of statements in the next several sections of the course.

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Let's see some example c++ statements.

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The first statement is the declaration statement,

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which we've already seen in this course when we declared variables.

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In this example, we declare x2b of type integer.

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The second is a simple assignment statement,

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where we assign the literal expression 12 to favorite number.

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The third example is an expression statement.

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Note that is simply an expression with a semicolon at the end.

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It's a pretty useless statement though since we add 2 numbers, but don't do anything with the sum.

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The fourth example is x equals 2 * 5 is an assignment statement.

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First, we multiply 2 and 5 and store the product in x.

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Notice how expression are used to make up the statement.

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The next example is an if statement.

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If statements give you lots of power to control the flow of your program.

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We'll discuss if statements in detail.

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But you can see that we're comparing A and B.

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And if A is greater than B, then we execute the statement that displays to the console.

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So here you can see an example of a statement

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that contains another statement within it and is also made up of expressions.

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The final statement is simply a semicolon.

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This is the null statement and perform has no actions.

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You don't often used in all statement, but it can come in handy sometimes.