ARRAYS

1). An array is a collection of homogeneous elements.
2. An array is a derived data type.
3) Any array is like a built-in data types. All we have to do is to declare an array variable so that we can use it.

Example of Array to find the sum marks of n students

#include <stdio.h>
int main(){
     int marks[10],i,n,sum=0;
     printf("Enter number of students: ");
     scanf("%d",&n);
     for(i=0;i<n;++i){
          printf("Enter marks of student%d: ",i+1);
          scanf("%d",&marks[i]);
          sum+=marks[i];
     }
     printf("Sum= %d",sum);
return 0;
}

Structures
1) An array is a collection of hetrogeneous elements.
2) A structure is a user-defined data type.
3) In the case of structure, first we have to design and declare a data structure and then we declare the variable of that type.
Example of Structure which stores record of a student for e.g. name,roll no and marks

#include <stdio.h>
struct student{
    char name[50];
    int roll;
    float marks;
};
int main(){
    struct student s;
    printf("Enter information of students:\n\n");
    printf("Enter name: ");
    scanf("%s",s.name);
    printf("Enter roll number: ");
    scanf("%d",&s.roll);
    printf("Enter marks: ");
    scanf("%f",&s.marks);
    printf("\nDisplaying Information\n");
    printf("Name: %s\n",s.name);
    printf("Roll: %d\n",s.roll);
    printf("Marks: %.2f\n",s.marks);
    return 0;
}