lesson 6

A simple C++ statement is each of the individual instructions of a program, like the variable declarations and expressions seen in previous sections. They always end with a semicolon (;), and are executed in the same order in which they appear in a program.

But programs are not limited to a linear sequence of statements. During its process, a program may repeat segments of code, or take decisions and bifurcate. For that purpose, C++ provides flow control statements that serve to specify what has to be done by our program, when, and under which circumstances.

Many of the flow control statements explained in this section require a generic (sub)statement as part of its syntax. This statement may either be a simple C++ statement, -such as a single instruction, terminated with a semicolon (;) - or a compound statement. A compound statement is a group of statements (each of them terminated by its own semicolon), but all grouped together in a block, enclosed in curly braces: {}:

{ statement1; statement2; statement3; }

The entire block is considered a single statement (composed itself of multiple substatements). Whenever a generic statement is part of the syntax of a flow control statement, this can either be a simple statement or a compound statement.


1. Selection Statements:

Conditional expressions are mainly used for decision making. C++ provides multiple selection structures: if, if/else, else if, nested if and switch.


2. The Single If Statement Structure:
The IF statement is used to express conditional expression. If the given condition is true then it will execute the statements; otherwise it will execute the optional statements.

3. The Single Block If Statement Structure :

The block IF statement are enclosed in ({) and (}) to group declaration and statements into a compound statement or a block. These blocks are always considered as a single statement.

4. The If/else Statement Structure:
In this case, either of the two statements are executed depending upon the value of the expression. Note that there is a semicolon after each of the statement but not after the IF expression.