In C++ a statement controls the sequence of execution, evaluates an expression, or does nothing (the null statement). All C++ statements e...
In C++ a statement controls the sequence of execution, evaluates an expression, or does nothing (the null statement). All C++ statements end with a semicolon, even the null statement, which is just the semicolon and nothing else. One of the most common statements is the following assignment statement:
x = a + b;
Unlike in algebra, this statement does not mean that x equals a+b. This is read, "Assign the value of the sum of a and b to x," or "Assign to x, a+b." Even though this statement is doing two things, it is one statement and thus has one semicolon. The assignment operator assigns whatever is on the right side of the equal sign to whatever is on the left side.
New Term: A null statement is a statement that does nothing.
Whitespace
Whitespace (tabs, spaces, and newlines) is generally ignored in statements. The assignment statement previously discussed could be written as
x=a+b;
or as
x =a
+ b ;
Although this last variation is perfectly legal, it is also perfectly foolish. Whitespace can be used to make your programs more readable and easier to maintain, or it can be used to create horrific and indecipherable code. In this, as in all things, C++ provides the power; you supply the judgment.
New Term: Whitespace characters (spaces, tabs, and newlines) cannot be seen. If these characters are printed, you see only the white of the paper.
Blocks and Compound Statements
Any place you can put a single statement, you can put a compound statement, also called a block. A block begins with an opening brace ({) and ends with a closing brace (}). Although every statement in the block must end with a semicolon, the block itself does not end with a semicolon. For example
{
temp = a;
a = b;
b = temp;
}
This block of code acts as one statement and swaps the values in the variables a and b.
DO use a closing brace any time you have an opening brace. DO end your statements with a semicolon. DO use whitespace judiciously to make your code clearer.
