Continue Statement

It is sometimes desirable to skip some statements inside the loop. In such cases, continue statements are used.

for (condition)

{ if (condition2)

continue;

// statements;

26. Switch multi-branching construct in the programming language C++.

A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case.

Syntax:

The syntax for a switch statement in C++ is as follows:

switch(expression){ case constant-expression: statement(s); break; //optional case constant-expression: statement(s); break; //optional   // you can have any number of case statements. default: //Optional statement(s); }

The following rules apply to a switch statement:

• The expression used in a switch statement 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.
• You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon.
• The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.
• When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
• When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.
• Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.
• A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.

27) Do while loop in the programming language C++.

In most computer programming languages, a while loop is a control flow statement that allows code to be executed repeatedly based on a given boolean condition. The while loop can be thought of as a repeating if statement.

The while construct consists of a block of code and a condition. The condition is evaluated, and if the condition is true, the code within the block is executed. This repeats until the condition becomes false. Because while loop checks the condition before the block is executed, the control structure is often also known as a pre-test loop. Compare with the do while loop, which tests the condition after the loop has executed.

For example, in the C programming language (as well as Java and C++, which use the same syntax in this case), the code fragment

int x = 0; while (x < 5)

{ printf ("x = %d \n ", x);(cout<<”x=”<<endl;) x++;}

The syntax for the do while control structure within the C++ programming language is:

do{ statement; statement; statement; statement; // This statement updates the flag;}while (expression);

EXAMPLE

do{ cout << "\nWhat is your age? ";

cin >> age_user; cout << "\nWhat is your friend's age? "; cin >> age_friend; cout >> "\nTogether your ages add up to: "; cout >> (age_user + age_friend); cout << "\nDo you want to do it again? y or n "; cin >> loop_response;} while (loop_response == 'y');

The three attributes of a test after loop are present. The action part consists of the 6 lines that prompt for data and then displays the total of the two ages. The update of the flag is the displaying the question and getting the answer for the variable loop_response. The test is the equality relational comparison of the value in the flag variable to the lower case character of y.

This type of loop control is called an event controlled loop. The flag updating is an event where someone decides if they want the loop to execute again.

28) Passing pointer and reference parameters to function in programming language C++.

A computer memory location has an address and a content. On the other hand, a variable is a named location that can store a value of a particular type. Typically, each address location can hold 8-bit (1-byte) of data. A 4-byte int value occupies 4 memory locations. A 32-bit system typically uses 32-bit addresses. To store a 32-bit address, 4 memory locations are required.

The following diagram illustrate the relationship between memory address and content; and variable's name, type and value.

Дата добавления: 2015-11-16