Using structures in C with user defined functions - c

Question

I had came across a problem that I have tried so many times with different ways but still not able to obtain the required solution please do help me.
PROBLEM: Define a structure to store students’ details. Pass them to a function where the student with HIGHEST CGPA is calculated from a set of 5 students. And display the result.(Here we have to store name, age and CGPA obtained of each student)
Here is my try at the problem:
#include <stdio.h>
void highCGPA(float b,struct detst D[4]);
struct detst
{
int age;
float CGPA;
char name[30];
};
int main()
{
struct detst D[4];
int i;
float h;
for(i=0;i<=4;i++)
{
printf("Enter the name of student %d:\n",i+1);
scanf("%s",&D[i].name);
printf("Enter the age of student %d:\n",i+1);
scanf("%d",&D[i].age);
printf("Enter the CGPA obtined by student %d:\n",i+1);
scanf("%f",&D[i].CGPA);
}
highCGPA(h,D);
}
void highCGPA(float b,struct detst D[4])
{
int i,max;
max = D[0].CGPA;
for(i=0;i<=4;i++)
{
if(D[i].CGPA > max)
{
max = D[i].CGPA;
}
}
printf("Highest CGPA obtained is:\n%f",max);
}

Answer 1

There is more than one problem. You're trying to store the data of 5 students in an array of struct with size 4. So:
struct detst D[5]; // fixed size
int i;
float h;
for(i=0;i<5;i++) { // EDIT (comments suggestion): for loop fix following standard convetions
/* take input */
}
Lastly, if you declare max as an int, you can't try to print it with a format specifier for float. So:
printf("Highest CGPA obtained is: %d\n",max); // format specifier for int is %d (not %f)

Answer 2

There are couple of other problems.
your declaration of funtion highCGPA is above your struct detst definition
you should have got error
error: array type has incomplete element type ‘struct detst’
declare your function after the structure definition.
your max variable is int in the function highCGPA , but you are trying to store a float value in it.

Answer 3

With a sligth change to program functionallity can be improved:
#include <float.h> // FLT_MAX
#include <stdio.h>
struct detst
{
int age;
float CGPA;
char name[30];
};
// Return offset of student with highest CGPA
int highCGPA(struct detst const (*D)[5]); // Using pointer to array
// to avoid degeneration
int main()
{
struct detst D[5];
int i;
for(i = 0; i < 5; i++)
{
printf("Enter the name of student %d:\n", i + 1);
scanf("%29s", D[i].name); // Make sure we don't overwrite the buffer
printf("Enter the age of student %d:\n", i + 1);
scanf("%d", &D[i].age);
printf("Enter the CGPA obtained by student %d:\n", i + 1);
scanf("%f", &D[i].CGPA);
}
int bestStudentOffset = highCGPA(&D); // By asking for best student
// we can obtain a lot more
printf(
"Best student is %d year old %s with\n",
D[bestStudentOffset].age,
D[bestStudentOffset].name);
printf("Highest CGPA obtained is:\n%f\n", D[bestStudentOffset].CGPA);
}
// Return offset of student with highest CGPA
int highCGPA(struct detst const (*D)[5])
{
int i, maxOffset = -1;
float max = -FLT_MAX;
for(i = 0; i < 5; i++)
{
if((*D)[i].CGPA > max)
{
max = (*D)[i].CGPA;
maxOffset = i;
}
}
return maxOffset;
}