# C program to store Student records as Structures and Sort them by Name

Last Updated : 17 Jan, 2019

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 ` `#include ` `#include ` ` `  `// 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

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