Write a C program to demonstrate passing structures to functions.

In C, structure can be passed to functions by two methods: 1) Passing by value (passing actual value as argument) 2) Passing by reference (passing address of an argument) Passing structure by value:

#include 
struct student{
    char name[50];
    int roll;
};
void Display(struct student stu);
/* function prototype should be below to the structure declaration otherwise compiler shows error */
int main(){
    struct student s1;
    printf("Enter student's name: ");
    scanf("%s",&s1.name);
    printf("Enter roll number:");
    scanf("%d",&s1.roll);
    Display(s1);   // passing structure variable s1 as argument
    return 0;
}
void Display(struct student stu){
  printf("Output\nName: %s",stu.name);
  printf("\nRoll: %d",stu.roll);
}
Output:
Enter student's name: Kevin Amla
Enter roll number: 149
Output
Name: Kevin Amla
Roll: 149

Passing structure by reference:

#include 
struct distance{
    int feet;
    float inch;
};
void Add(struct distance d1,struct distance d2, struct distance *d3); 
int main()
{
    struct distance dist1, dist2, dist3;
    printf("First distance\n");
    printf("Enter feet: ");
    scanf("%d",&dist1.feet);
    printf("Enter inch: ");
    scanf("%f",&dist1.inch);
    printf("Second distance\n");
    printf("Enter feet: ");
    scanf("%d",&dist2.feet);
    printf("Enter inch: ");
    scanf("%f",&dist2.inch);
    Add(dist1, dist2, &dist3); 

/*passing structure variables dist1 and dist2 by value whereas passing structure variable dist3 by reference */
    printf("\nSum of distances = %d\'-%.1f\"",dist3.feet, dist3.inch);
    return 0;
}
void Add(struct distance d1,struct distance d2, struct distance *d3) 
{
/* Adding distances d1 and d2 and storing it in d3 */
     d3->feet=d1.feet+d2.feet; 
     d3->inch=d1.inch+d2.inch;
     if (d3->inch>=12) {     /* if inch is greater or equal to 12, converting it to feet. */
         d3->inch-=12;
         ++d3->feet;
    }
}
Output:
First distance
Enter feet: 12
Enter inch: 6.8
Second distance
Enter feet: 5
Enter inch: 7.5

Sum of distances = 18'-2.3"