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:
C
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.
// 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:
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 CUnsorted 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