Tag: c++ memcpy

C++ Default Parameters

Default Parameter Value

You can also use a default parameter value, by using the equals sign (=).

If we call the function without an argument, it uses the default value (“Norway”):

Example

void myFunction(string country = "Norway") {
  cout << country << "\n";
}

int main() {
  myFunction("Sweden");
  myFunction("India");
  myFunction();
  myFunction("USA");
  return 0;
}

// Sweden
// India
// Norway
// USA

A parameter with a default value, is often known as an “optional parameter“. From the example above, country is an optional parameter and "Norway" is the default value.

Continue reading C++ Default Parameters

C++ Function Parameters

Parameters and Arguments

Information can be passed to functions as a parameter. Parameters act as variables inside the function.

Parameters are specified after the function name, inside the parentheses. You can add as many parameters as you want, just separate them with a comma: Continue reading C++ Function Parameters

C++ Functions

A function is a block of code which only runs when it is called.

You can pass data, known as parameters, into a function.

Functions are used to perform certain actions, and they are important for reusing code: Define the code once, and use it many times.

Continue reading C++ Functions

C++ Dereference

Get Memory Address and Value

In the example from the previous page, we used the pointer variable to get the memory address of a variable (used together with the & reference operator). However, you can also use the pointer to get the value of the variable, by using the * operator (the dereference operator): Continue reading C++ Dereference

C++ Pointers

Creating Pointers

You learned from the previous chapter, that we can get the memory address of a variable by using the & operator:

Example

string food = "Pizza"; // A food variable of type string

cout << food;  // Outputs the value of food (Pizza)
cout << &food; // Outputs the memory address of food (0x6dfed4)

A pointer however, is a variable that stores the memory address as its value.

A pointer variable points to a data type (like int or string) of the same type, and is created with the * operator. The address of the variable you’re working with is assigned to the pointer: Continue reading C++ Pointers

C++ Memory Address

Memory Address

In the example from the previous page, the & operator was used to create a reference variable. But it can also be used to get the memory address of a variable; which is the location of where the variable is stored on the computer.

When a variable is created in C++, a memory address is assigned to the variable. And when we assign a value to the variable, it is stored in this memory address.

To access it, use the & operator, and the result will represent where the variable is stored: Continue reading C++ Memory Address

C++ References

Creating References

A reference variable is a “reference” to an existing variable, and it is created with the & operator:

string food = "Pizza";  // food variable
string &meal = food;    // reference to food

Now, we can use either the variable name food or the reference name meal to refer to the food variable: Continue reading C++ References

C++ Enumeration

C++ Enums

An enum is a special type that represents a group of constants (unchangeable values).

To create an enum, use the enum keyword, followed by the name of the enum, and separate the enum items with a comma:

enum Level {
  LOW,
  MEDIUM,
  HIGH
};

Note that the last item does not need a comma.

It is not required to use uppercase, but often considered as good practice.

Enum is short for “enumerations”, which means “specifically listed”.

Continue reading C++ Enumeration

C++ Structures (struct)

C++ Structures

Structures (also called structs) are a way to group several related variables into one place. Each variable in the structure is known as a member of the structure.

Unlike an array, a structure can contain many different data types (int, string, bool, etc.).

Create a Structure

To create a structure, use the struct keyword and declare each of its members inside curly braces.

After the declaration, specify the name of the structure variable (myStructure in the example below):

struct {             // Structure declaration
  int myNum;         // Member (int variable)
  string myString;   // Member (string variable)
} myStructure;       // Structure variable

Access Structure Members

To access members of a structure, use the dot syntax (.):

Example

Assign data to members of a structure and print it:

// Create a structure variable called myStructure
struct {
  int myNum;
  string myString;
} myStructure;

// Assign values to members of myStructure
myStructure.myNum = 1;
myStructure.myString = "Hello World!";

// Print members of myStructure
cout << myStructure.myNum << "\n";
cout << myStructure.myString << "\n";

One Structure in Multiple Variables

You can use a comma (,) to use one structure in many variables:

struct {
  int myNum;
  string myString;
} myStruct1, myStruct2, myStruct3; // Multiple structure variables separated with commas

This example shows how to use a structure in two different variables:

Example

Use one structure to represent two cars:

struct {
  string brand;
  string model;
  int year;
} myCar1, myCar2; // We can add variables by separating them with a comma here

// Put data into the first structure
myCar1.brand = "BMW";
myCar1.model = "X5";
myCar1.year = 1999;

// Put data into the second structure
myCar2.brand = "Ford";
myCar2.model = "Mustang";
myCar2.year = 1969;

// Print the structure members
cout << myCar1.brand << " " << myCar1.model << " " << myCar1.year << "\n";
cout << myCar2.brand << " " << myCar2.model << " " << myCar2.year << "\n";

Named Structures

By giving a name to the structure, you can treat it as a data type. This means that you can create variables with this structure anywhere in the program at any time.

To create a named structure, put the name of the structure right after the struct keyword:

struct myDataType { // This structure is named "myDataType"
  int myNum;
  string myString;
};

To declare a variable that uses the structure, use the name of the structure as the data type of the variable:

myDataType myVar;

Example

Use one structure to represent two cars:

// Declare a structure named "car"
struct car {
  string brand;
  string model;
  int year;
};

int main() {
  // Create a car structure and store it in myCar1;
  car myCar1;
  myCar1.brand = "BMW";
  myCar1.model = "X5";
  myCar1.year = 1999;

  // Create another car structure and store it in myCar2;
  car myCar2;
  myCar2.brand = "Ford";
  myCar2.model = "Mustang";
  myCar2.year = 1969;
 
  // Print the structure members
  cout << myCar1.brand << " " << myCar1.model << " " << myCar1.year << "\n";
  cout << myCar2.brand << " " << myCar2.model << " " << myCar2.year << "\n";
 
  return 0;
}