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:

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.

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;

    p = getData(p);   
    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 same as program above.

In this program, the structure variable p of type structure Person is defined under main() function.

The structure variable p is passed to getData() function which takes input from user which is then returned to main function.

p = getData(p);

Note: The value of all members of a structure variable can be assigned to another structure using assignment operator = if both structure variables are of same type. You don’t need to manually assign each members.

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