Given student’s records with each record containing id, name and age of a student. Write a C program to read these records and display them in sorted order by name.
Examples:
Input: Student Records= { {Id = 1, Name = bd, Age = 12 }, {Id = 2, Name = ba, Age = 10 }, {Id = 3, Name = bc, Age = 8 }, {Id = 4, Name = aaz, Age = 9 }, {Id = 5, Name = az, Age = 10 } } Output: {{Id = 4, Name = aaz, Age = 9 }, {Id = 5, Name = az, Age = 10 }, {Id = 2, Name = ba, Age = 10 }, {Id = 3, Name = bc, Age = 8 }, {Id = 1, Name = bd, Age = 12 } }
Approach: This problem is solved in following steps:
- Create a structure with fields id, name and age.
- Read the students records in the structure
- Define a comparator by setting up rules for comparison. Here names can be sorted by the help of strcmp() method.
- Now sort the structure based on the defined comparator with the help of qsort() method.
- Print the sorted students records.
Program:
// C program to read Student records // like id, name and age, // and display them in sorted order by Name #include <stdio.h> #include <stdlib.h> #include <string.h> // struct person with 3 fields struct Student {
char * name;
int id;
char age;
}; // setting up rules for comparison // to sort the students based on names int comparator( const void * p, const void * q)
{ return strcmp ((( struct Student*)p)->name,
(( struct Student*)q)->name);
} // Driver program int main()
{ int i = 0, n = 5;
struct Student arr[n];
// Get the students data
arr[0].id = 1;
arr[0].name = "bd" ;
arr[0].age = 12;
arr[1].id = 2;
arr[1].name = "ba" ;
arr[1].age = 10;
arr[2].id = 3;
arr[2].name = "bc" ;
arr[2].age = 8;
arr[3].id = 4;
arr[3].name = "aaz" ;
arr[3].age = 9;
arr[4].id = 5;
arr[4].name = "az" ;
arr[4].age = 10;
// Print the Unsorted Structure
printf ( "Unsorted Student Records:\n" );
for (i = 0; i < n; i++) {
printf ( "Id = %d, Name = %s, Age = %d \n" ,
arr[i].id, arr[i].name, arr[i].age);
}
// Sort the structure
// based on the specified comparator
qsort (arr, n, sizeof ( struct Student), comparator);
// Print the Sorted Structure
printf ( "\n\nStudent Records sorted by Name:\n" );
for (i = 0; i < n; i++) {
printf ( "Id = %d, Name = %s, Age = %d \n" ,
arr[i].id, arr[i].name, arr[i].age);
}
return 0;
} |
Output:
Unsorted Student Records: Id = 1, Name = bd, Age = 12 Id = 2, Name = ba, Age = 10 Id = 3, Name = bc, Age = 8 Id = 4, Name = aaz, Age = 9 Id = 5, Name = az, Age = 10 Student Records sorted by Name: Id = 4, Name = aaz, Age = 9 Id = 5, Name = az, Age = 10 Id = 2, Name = ba, Age = 10 Id = 3, Name = bc, Age = 8 Id = 1, Name = bd, Age = 12
Note: The structures can be sorted according to any field, based on the rules defined in the comparator function. To know more about comparator function. refer Comparator function of qsort() in C