Sometimes it is necessary in the program to execute the statement several times, and C++ loops execute a block of commands a specified number of times until a condition is met. In this post, you will learn about all the looping statements of C++ along with their use.

Loops in C++

There may arise some situations during programming where programmers need to execute the block of code several times (with slight variations sometimes). In general, statements get executed sequentially with a C++ program, one statement followed by another. C++ provides statements for several control structures along with iteration/repetition capability that allows programmers to execute a statement or group of statements multiple times.

All are slightly different and provides loops for different situations.

Figure – Flowchart of Looping:

C++ Loop Control Statements

Loop control statements are used to change the normal sequence of execution of a loop.

COPY CODE SNIPPET

As we all know functions play an important role in programming. Driving programs into functions is one of the major principles of programming. In C, they are called functions but in C++ they are termed as member functions. In this tutorial you will learn about the member function and its concept used in C++

What are Member Functions in C++?

Member functions are C++ functions that have their declarations inside the class definition and these member functions work on the data member of the class. Member function definition can be written inside or outside the definition of the class. If the definition of member function is inside the class definition, then it can e defined directly, but if it is defined outside the class then a special operator name scope resolution operator (::) is used along with the name of the class and the function name.

class Sq {public:    int a;    int square(); // Declaring function square with no argument and having return type 'int'.};int Sq::square(){    return a * a;}

In this case, if you define the member function outside the class definition, then you must declare the function inside class definition and then define it outside using the scope resolution operator.

or

class Sq {public:    int a;    int square()    {        return a * a; //returns square of a number    }};

In the above program, the function is defined inside the class and so you do not need to declare it first and can directly define the function.

main() Function of C++

The main() function is called when the program starts after initialization of the non-local objects with static storage duration. It is the primary entry point of any C++ program that is executed in the hosted environment. In C++, the main() function is written after the class definition. The main function of C++ has several special properties. These are:

1. main() function cannot be used anywhere within the program
   1. In particular, cannot be called recursively
   2. Its address cannot be taken for reuse
2. main() function cannot be predefined and cannot be overloaded.
3. main() function cannot be declared as static, inline or constexpr
4. The return type of the main() function cannot be deduced (i.e. auto main() {… is not allowed in C++).

The main() function for both the function definition (discussed above) will be same. You have to create objects of the class inside the main() and using that object along with the dot (.) operator member functions will be called.

return_type main(){    class_name object - declaration;    object_name.memberfunction1_name();    object_name.memberfunction2_name();    ........}

int main(){    Sq S1;    S1.a = 6;    S1.square();    cout << " Square of the number is :"<< S1.square();}

Types of Member Functions in C++

As we are now familiar with what are member function and how they are declared and defined, how they are used in a C++ program to handle data member and member functions, and how they are called from the main(); it is time to know what are the different types of member function provided by C++.

Simple Member Functions

As discussed earlier, these are simple functions of C++ with or without return type and with or without parameters. The basic structure of a simple member function is:

return_type functionName(parameter_list){    // function body;}

Static Member Functions

The keyword ‘static‘ is used with such member functions. Static is mainly used to hold its positions. These functions work for the whole class rather than for a particular object of the class.

class X {public:    static void k(){};};int main(){    G::k(); // calling member function directly with class name}

The static member functions cannot access ordinary data members and member functions, but can only access the static data members and static member functions of a class.

Const Member Function

Const keyword makes variable constant, which means once defined, their value cannot be changed. The basic syntax of const member function is:

void fun() const{}

Inline Function

When a function is declared as inline, the compiler places a copy of the code of that specific function at each point where the function is called at compile time.

Friend Function

Functions are declared as the friend using the keyword ‘friend’ to give private access to non-class functions. Programmers can declare a global function as a friend, or a member function of other class as a friend.

Data types in any of the language mean that what are the various type of data the variables can have in that particular language. Information is stored in a computer memory with different data types. Whenever a variable is declared it becomes necessary to define the data type that what will be the type of data that variable can hold.

Both C and C++ compilers support the fundamental i.e. the built-in data types. Taking void as exception, the basic data types may have several modifiers, and these modifiers are used to serve the data types in various situations.

Character Data Types

Integer Data Types

Floating-point Data Types

Boolean Data Type

Below example will produce correct size of various data type, on your computer.

#include <iostream>using namespace std;int main() { cout << "Size of char is " << sizeof(char) << endl; cout << "Size of int is " << sizeof(int) << endl; cout << "Size of float is " << sizeof(float) << endl; cout << "Size of short int is " << sizeof(short int) << endl; cout << "Size of long int is " << sizeof(long int) << endl; cout << "Size of double is " << sizeof(double) << endl; cout << "Size of wchar_t is " << sizeof(wchar_t) << endl; return 0;}

Size of char is 1Size of int is 4Size of float is 4Size of short int is 2Size of long int is 4Size of double is 8Size of wchar_t is 4

Enum Data Type

This is an user defined data type having finite set of enumeration constants. The keyword ‘enum‘ is used to create enumerated data type.

Syntax:

enum enum-name {list of names}var-list;

enum mca(software, internet, seo);

Typedef

It is used to create new data type. But it is commonly used to change existing data type with another name.

Syntax:

typedef [data_type] synonym;

typedef [data_type] new_data_type;

typedef int integer;integer rollno;

What are Constants?

Constants are like a variable, except that their value never changes during the program execution once defined. Constants refer to as fixed values, unlike variables whose value can be altered, constants – as the name implies does not change, they remain constant. Constant must have to be initialized at the time of creating it and new values cannot be assigned later to it.

Constant Definition in C++

There are two other different ways to define constants in C++. These are:

• By using const keyword
• By using #define preprocessor

Constant Definition by Using const Keyword

const type constant_name;

#include <iostream>using namespace std;int main(){  const int SIDE = 50;  int area;  area = SIDE*SIDE;  cout<<"The area of the square with side: " << SIDE <<" is: " << area << endl;  system("PAUSE");  return 0;}

int const SIDE = 50;

const int SIDE = 50;

#define constant_name;

#include <iostream>using namespace std;#define VAL1 20   #define VAL2  6#define Newline '\n'int main(){   int tot;    tot = VAL1 * VAL2;   cout << tot;   cout << Newline;}