C++ Structure and Function

Structure variables can be passed to a function and returned in a similar way as normal arguments.

Passing structure to function in C++

A structure variable can be passed to a function in similar way as normal argument. Consider this example:

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Example 1: C++ Structure and Function

#include <iostream>
using namespace std;

struct Person {
    char name[50];
    int age;
    float salary;
};

void displayData(Person);   // Function declaration

int main() {
    Person p;

    cout << "Enter Full name: ";
    cin.get(p.name, 50);
    cout << "Enter age: ";
    cin >> p.age;
    cout << "Enter salary: ";
    cin >> p.salary;

    // Function call with structure variable as an argument
    displayData(p);

    return 0;
}

void displayData(Person p) {
    cout << "\nDisplaying Information." << endl;
    cout << "Name: " << p.name << endl;
    cout <<"Age: " << p.age << endl;
    cout << "Salary: " << p.salary;
}

Output

Enter Full name: Bill Jobs
Enter age: 55
Enter salary: 34233.4

Displaying Information.
Name: Bill Jobs
Age: 55
Salary: 34233.4

In this program, user is asked to enter the name, age and salary of a Person inside main() function.

Then, the structure variable p is to passed to a function using.

displayData(p);

The return type of displayData() is void and a single argument of type structure Person is passed.

Then the members of structure p is displayed from this function.

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Example 2: Returning structure from function in C++

#include <iostream>
using namespace std;

struct Person {
    char name[50];
    int age;
    float salary;
};

Person getData(Person); 
void displayData(Person); 

int main() {

    Person p, temp;

    temp = getData(p);
    p = temp;
    displayData(p);

    return 0;
}

Person getData(Person p) {

    cout << "Enter Full name: ";
    cin.get(p.name, 50);

    cout << "Enter age: ";
    cin >> p.age;

    cout << "Enter salary: ";
    cin >> p.salary;

    return p;
}

void displayData(Person p) {
    cout << "\nDisplaying Information." << endl;
    cout << "Name: " << p.name << endl;
    cout <<"Age: " << p.age << endl;
    cout << "Salary: " << p.salary;
}

The output of this program is the same as the program above.

In this program, we have created two structure variables p and temp of type Person under the main() function.

The structure variable p is passed to getData() function which takes input from the user which is then stored in the temp variable.

temp = getData(p); 

We then assign the value of temp to p.

p = temp;

Then the structure variable p is passed to displayData() function, which displays the information.

Note: We don't really need to use the temp variable for most compilers and C++ versions. Instead, we can simply use the following code:

p = getData(p);