Using structure, input some students' Name, Id and CGPA and sort them by Name, Id and CGPA respectively.

#include<stdio.h>
#include<string.h>
#define SIZE 5

struct diu_cse
{
    char name[20];
    int id;
    float cgpa;
};

struct diu_cse student[SIZE];

void input(struct diu_cse student[])
{
    int i;
    printf("***********Input************\n");
    for(i=0;i<SIZE;i++){
        scanf("%s%d%f", student[i].name, &student[i].id, &student[i].cgpa);
    }
}

void output(struct diu_cse student[])
{
    int i;
    for(i=0;i<SIZE;i++){
        printf("%10s    %5d    %.2f\n", student[i].name, student[i].id, student[i].cgpa);

    }
}

void sort_name_student(struct diu_cse student[])
{
    int i,j;
    for(i=0;i<SIZE-1;i++){
        for(j=i+1;j<SIZE;j++){
            if(strcmp(student[i].name , student[j].name)>0){
                struct diu_cse temp;

                strcpy(temp.name , student[i].name);
                temp.id = student[i].id;
                temp.cgpa = student[i].cgpa;

                strcpy(student[i].name , student[j].name);
                student[i].id = student[j].id;
                student[i].cgpa = student[j].cgpa;

                strcpy(student[j].name , temp.name);
                student[j].id = temp.id;
                student[j].cgpa = temp.cgpa;
            }
        }
    }
}

void sort_cgpa_student(struct diu_cse student[])
{
    int i,j;
    for(i=0;i<SIZE-1;i++){
        for(j=i+1;j<SIZE;j++){
            if(student[i].cgpa < student[j].cgpa){
                struct diu_cse temp;

                strcpy(temp.name , student[i].name);
                temp.id = student[i].id;
                temp.cgpa = student[i].cgpa;

                strcpy(student[i].name , student[j].name);
                student[i].id = student[j].id;
                student[i].cgpa = student[j].cgpa;

                strcpy(student[j].name , temp.name);
                student[j].id = temp.id;
                student[j].cgpa = temp.cgpa;
            }
        }
    }
}

void sort_id_student(struct diu_cse student[])
{
    int i,j;
    for(i=0;i<SIZE-1;i++){
        for(j=i+1;j<SIZE;j++){
            if(student[i].id > student[j].id){
                struct diu_cse temp;

                strcpy(temp.name , student[i].name);
                temp.id = student[i].id;
                temp.cgpa = student[i].cgpa;

                strcpy(student[i].name , student[j].name);
                student[i].id = student[j].id;
                student[i].cgpa = student[j].cgpa;

                strcpy(student[j].name , temp.name);
                student[j].id = temp.id;
                student[j].cgpa = temp.cgpa;
            }
        }
    }
}

int main()
{
    input(student);

    sort_name_student(student);
    printf("*********** Sort By Name ************\n");
    output(student);

    sort_id_student(student);
    printf("*********** Sort By Id ************\n");
    output(student);

    sort_cgpa_student(student);
    printf("*********** Sort By CGPA ************\n");
    output(student);

}

Output:

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