About my program in C

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<conio.h>

#define Student struct Stud

void add(FILE * fp); 				//to add to list
FILE * del(FILE * fp);				//to delete from list
void modify(FILE * fp);				//to modify a record
void displayList(FILE * fp);		//display whole list
void searchRecord(FILE *fp);		//find a particular record
void printChar(char ch,int n);		//printing a character ch n times
void printHead();					//printing head line for each screen

struct Stud
{
    char name[100];
    char branch[50];
    int roll;
	char assignment; float sgpa[8];
   float cgpa;
}tm;


int main()
{
 FILE * fp;
Student s;
int option;
char another;

if((fp=fopen("studentInfo.txt","rb+"))==NULL)
{
    if((fp=fopen("studentInfo.txt","wb+"))==NULL)
       {
           printf("can't open file");
           return 0;
       }
}

printHead();
printf("\n\n\t\tCREATED BY");
printf("\n\n\t\tSushant Karki");
printf("\n\n\t\tSrijal K.C.");
printf("\n\n\t\tRuxana Maharjan\n");

printf("\n\t\tPRESS ANY KEY TO CONTINUE");
getch();

while(1)
{
    printHead();
    printf("\n\t");
    printChar('-',64);
	printf("\n\n\t\t\t1. ADD Student");
    printf("\n\n\t\t\t2. DELETE Student");
    printf("\n\n\t\t\t3. MODIFY Student");
    printf("\n\n\t\t\t4. DISPLAY Student List");
    printf("\n\n\t\t\t5. Search Record");
    printf("\n\n\t\t\t0. EXIT");

    printf("\n\n\t\tEnter Your Option : ");
    scanf("%d",&option);

    switch(option)
    {
        case 0: return 1;
                break;
        case 1: add(fp);
                break;
        case 2: fp=del(fp);
                break;
        case 3: modify(fp);
                break;
        case 4: displayList(fp);
                break;
        case 5: searchRecord(fp);
                break;
        default: printf("\n\t\tYou Pressed wrong key");
                  printf("\n\t\tProgram terminated");
                  getch();
                  exit(0);

    }
}
return 1;

}

//----printing character ch at n times ------

void printChar(char ch,int n)
{
    while(n--)
    {
        putchar(ch);
    }
}

//-----Printing Head Line of the program -----

void printHead()
{ system("cls");

printf("\n\n\t");
printChar('=',16);
printf("[STUDENT] [INFORMATION] [SYSTEM]");
printChar('=',16);
printf("\n");
}


// ==========ADDING NEW RECORD==========================


void add(FILE * fp)
{


printHead();
printf("\n\t");
    printChar('-',64);
    printf("\t\tTo add information please input username and password\n\n");

char another='y';
Student s;
int i;
char assignment;
//float cgpa;
int conf_record(char id[])
fseek(fp,0,SEEK_END);
char name[20];
char password[10];
printf("\t\tEnter username: ");
scanf("%s",name);
printf("\t\tEnter password: ");
scanf("%s",password);
if (strcmp(name, "abc") == 0 && strcmp(password, "abc") == 0)
{
printf("\t\tPermission Granted\n");
while(another=='y'||another=='Y')
{

    printf("\n\n\t\tEnter Full Name of Student:\t");
    fflush(stdin);
    fgets(s.name,100,stdin); //fgets takes an extra \n character as input
    s.name[strlen(s.name)-1]='\0';

    printf("\n\n\t\tEnter Department:\t");
    fflush(stdin);
    fgets(s.branch,50,stdin);
    s.branch[strlen(s.branch)-1]='\0';
	fread(&tm,sizeof(tm),1,fp);
	do{

    printf("\n\n\t\tEnter Roll number:\t");
    fflush(stdin);
	scanf("%d",&s.roll);
	if(tm.roll==s.roll)
	break;

 }while(fread(&tm,sizeof(tm),1,fp)==1);

	fwrite(&s,sizeof(s),1,fp);

//printf("\n\n\n\t Enter The assignment:\t);
    //scanf("%s", &s.assignment);
    //fwrite(&s, sizeof(s), 1, fp);

    printf("\n\n\t\tWant to enter another student info (Y/N)\t");
    fflush(stdin);
    another=getchar();
}
}
else
{
printf("\t\tWrong passsword!!\n\t\tPress Any Key\n");
exit;
}


getch();
}




//===================DELETING A RECORD FROM LIST ============
FILE * del(FILE * fp)
{
 printHead();
 	printf("\n\t");
    printChar('-',64);
    printf("\t\tTo delete information please input username and password\n\n");

Student s;
int flag=0,tempRoll,siz=sizeof(s);
FILE *ft;

if((ft=fopen("temp.txt","wb+"))==NULL)
{
    printf("\n\n\t\t\t\\t!!! ERROR !!!\n\t\t");
    system("pause");
     return fp;
}
char name[20];
char password[10];
printf("\t\tEnter username: ");
scanf("%s",name);
printf("\t\tEnter password: ");
scanf("%s",password);
if (strcmp(name, "abc") == 0 && strcmp(password, "abc") == 0)
{
printf("\t\tPermission granted\n");
printf("\n\n\tEnter Roll number of Student to Delete the Record");
printf("\n\n\t\t\tRoll No. : ");
scanf("%d",&tempRoll);

rewind(fp);


while((fread(&s,siz,1,fp))==1)
{
    if(s.roll==tempRoll)
    { flag=1;
    printf("\n\tRecord Deleted for");
    printf("\n\n\t\t%s\n\n\t\t%s\n\n\t\t%d\n\t",s.name,s.branch,s.roll);
    continue;
    }

    fwrite(&s,siz,1,ft);
}


fclose(fp);
fclose(ft);

remove("studentInfo.txt");
rename("temp.txt","studentInfo.txt");

if((fp=fopen("studentInfo.txt","rb+"))==NULL)
{
    printf("ERROR");
    return  NULL;
}

if(flag==0) printf("\n\n\t\t!!!! ERROR RECORD NOT FOUND \n\t");

printChar('-',65);
printf("\n\t");
system("pause");
return fp;

}
else
{
printf("\t\tWrong passsword!!\n\t\tPress Any Key\n");
exit;
}

getch();

}


//===========MODIFY A RECORD ===========================

void modify(FILE * fp)
{
printHead();
	printf("\n\t");
    printChar('-',64);
    printf("\t\tTo modify information please input username and password\n\n");
Student s;
int i,flag=0,tempRoll,siz=sizeof(s);
//float cgpa;
char name[20];
char password[10];
printf("\t\tEnter username: ");
scanf("%s",name);
printf("\t\tEnter password: ");
scanf("%s",password);
if (strcmp(name, "abc") == 0 && strcmp(password, "abc") == 0)
{
printf("\t\tPermission granted\n");
printf("\n\n\tEnter Roll Number of Student to MODIFY the Record : ");
scanf("%d",&tempRoll);

rewind(fp);

while((fread(&s,siz,1,fp))==1)
{
    if(s.roll==tempRoll)
        {flag=1;
        break;
        }
}

if(flag==1)
    {
    fseek(fp,-siz,SEEK_CUR);
    printf("\n\n\t\tRECORD FOUND");
    printf("\n\n\t\tEnter New Data for the Record");

    printf("\n\n\t\tEnter Full Name of Student\t");
    fflush(stdin);
    fgets(s.name,100,stdin);
    s.name[strlen(s.name)-1]='\0';

    printf("\n\n\t\tEnter Branch\t");
    fflush(stdin);
    fgets(s.branch,50,stdin);
    s.branch[strlen(s.branch)-1]='\0';

    printf("\n\n\t\tEnter Roll number \t");
    scanf("%d",&s.roll);




    fwrite(&s,sizeof(s),1,fp);
}

else printf("\n\n\t!!!! ERROR !!!! RECORD NOT FOUND");

printf("\n\n\t");
system("pause");

}
else
{
printf("\t\tWrong passsword!!\n\t\tPress Any Key\n");
exit;
}

getch();


}

//====================DISPLAY THE LIST =================
void displayList(FILE * fp)
{   printHead();
    Student s;
    int i,siz=sizeof(s);

    rewind(fp);

    while((fread(&s,siz,1,fp))==1)
    {
        printf("\n\t\tNAME : %s",s.name);
        printf("\n\n\t\tBRANCH : %s",s.branch);
        printf("\n\n\t\tROLL : %d\n",s.roll );
        printChar('-',64);
		}
    printf("\n\n\n\t");
     printChar('*',65);
    printf("\n\n\t");
    system("pause");
}

void searchRecord(FILE *fp)
{printHead();

int tempRoll,flag,siz,i;
Student s;
char another='y';

siz=sizeof(s);

while(another=='y'||another=='Y')
{
printf("\n\n\tEnter Roll Number of Student to search the record : ");
scanf("%d",&tempRoll);

rewind(fp);

while((fread(&s,siz,1,fp))==1)
{
    if(s.roll==tempRoll)
        {flag=1;
        break;
        }
}

if(flag==1)
    {
    printf("\n\t\tNAME : %s",s.name);
        printf("\n\n\t\tBRANCH : %s",s.branch);
        printf("\n\n\t\tROLL : %d",s.roll);

}
else printf("\n\n\t\t!!!! ERROR RECORD NOT FOUND !!!!");


printf("\n\n\t\tWant to enter another search (Y/N)");
fflush(stdin);
another=getchar();
}
}