my code is giving linking errors can anyone help!

Code:

Code:

//*Hira Daud
// regn no=83
//BICSE 4-A*/ 




#include<iostream>
#include<string>
using namespace std;

struct student
{
	float sum;
    float  numbgrade;
	char course;
	char section_number;
    double reg_no;
	string name;
	int progass[4];
	int test[4];
	int homeass[4];
	float progav;
	float testav;
	float homeav;

};

void swap(int *,int *);
 bool  ascending(int ,int );
void bubble(float ,const int size,bool   (*compare)(int,int));
void lettergrade(float *);    //prototypes 
      
int main()
{
	double testwgt,homewgt,progwgt;
	testwgt=0.6;
	homewgt=0.2;
	progwgt=0.2;


  const int a=40;
  student student1[a];
  for (int i=0;i<a;i++)
  {
	  cout<<"please enter your name\t:";
	 
	  cin>>student1[i].name;
	
	  cout<<"\nenter your section number\t:";
	  cin>>student1[i].section_number;
	  
	  cout<<"\nenter your registration number\t:";
	  cin>>student1[i].reg_no;
	  
	  cout<<"plz enter ur crs identifier\n";
	  cin>>student1[i].course;
	  
	   
  
student1[i].testav=student1[i].progav=student1[i].homeav=student1[i].sum=0; //initializing
   for(int j=0;j<4;j++)
   {
	  cout<<"enter the marks of ur tests\n";
	  cin>>student1[i].test[j];
	  student1[i].testav+=student1[i].test[j];

	  cout<<"enter the marks of ur programming asssignments\t\n";
	  cin>>student1[i].progass[j];
	  student1[i].progav+=student1[i].progass[j];

	  cout<<"enter the marks of ur home assignments\n\t";
	  cin>>student1[i].homeass[j];
	  student1[i].homeav+=student1[i].homeass[j];
   }//end of the nested loop
   
  student1[i].testav/=4;

  student1[i].homeav/=4;

  student1[i].progav/=4;

  student1[i].sum = student1[i].testav+student1[i].progav+student1[i].homeav;

  if(student1[i].sum>1)
 	  cout<<"there s some error"<<endl;
 else
	  cout<<"calculate the numeric grade"<<endl;
  
  for(int i=0;i<40;i++)
  {
  
student1[i].numbgrade=testwgt*student1[i].testav+progwgt*student1[i].progav+homewgt*student1[i].homeav;
  lettergrade(&student1[i].numbgrade);
  }

 }//end of for loop
  bubble(student1[i].numbgrade,a,ascending);

  cout<<"the highest numeric grade achieved by the student\n"<<student1[39].numbgrade<<endl;
  cout<<"the lowest grade is\n"<<student1[0].numbgrade;

return 0;
}


  void lettergrade(float *grade)
  {
	  if(*grade>93&&*grade<100)
		  cout<<"ur grade s A"<<endl;
	  else if (*grade>85&&*grade<92)
		  cout<<"ur grade s B"<<endl;
	  else if(*grade>77&&*grade<84)
		  cout<<"ur grade s C"<<endl;
	  else if(*grade>70&&*grade<76)
		  cout<<"ur grade s D"<<endl;
	  else 
		  cout<<"ur fail"<<endl;
  }
  //function definition for calculating the letter grade


void bubble(int stud[],const int size,bool (*compare)(int,int))
{
	for  (int a=1;a<size;a++)
	{
		for(int b=0;b<size-1;b++)
			if((*compare)(stud[b],stud[b+1]))
				swap(&stud[b], &stud[b+1]);
	}
	
}
void swap(int *c,int *d)
{
	int hold=*c;
	*c=*d;
	*d=hold;
}


bool ascending(int p,int q)
{
	return q<p;
}

what is the error?

The prototype for bubble doesn't seem to match the definition.

can you please indicate what is wrong with prototype ! i am still unable to execute the code

Code:

void bubble(float ,const int size,bool   (*compare)(int,int))
void bubble(int stud[],const int size,bool (*compare)(int,int))

bubble(student1[i].numbgrade,a,ascending);

See any difference?
No idea what you mean by sorting one float.

I guess it's not your own code.

yes you are right it is my friend code can you please help then !
sorry for saying that it my code! i write it my code by mistake

The prototype and definition must match. That's all you have to do is make them match to fix that specific error.