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";
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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";
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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;
}
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