C++ In a Nutshell

Selections

A selection statement chooses one branch from multiple possibilities and executes the statements in that branch. The two selection statements supported by C++ are if and switch.

if Statements

An if statement has one of the following forms:

if (condition ) statement

or:

if (condition ) statement else statement

In the first form, the condition is converted to a bool, and if it is true, the statement is executed. Otherwise, the statement is skipped, and execution continues with the subsequent statement.

The second form chooses one of two alternative code paths. The condition is converted to a bool, and if it is true, the first statement is executed. Otherwise, the second statement is executed. Declarations in the first statement are not visible in the second. If if statements are nested, the else part binds with the closest, preceding if statement. Example 4-3 shows nested if statements.

Example 4-3. Nested if statements

if (c1)
  if (c2)
    cout << "c1 and c2 are true\n";
  else
    cout << "c1 is true, but c2 is false\n";
else if (c2)
  cout << "c1 is false, but c2 is true\n";
else
  cout << "c1 and c2 are false\n";

switch Statements

A switch statement chooses one execution path from among many alternatives. The syntax is:

switch (condition ) statement

The condition must have an integral or enumerated type, or be of a class type in which the class has a single conversion function to an integral or enumerated type. The condition is evaluated once. Its value is compared against the case labels ...