Stuck on program

[SweetOne]

I keep getting an invalid selection printing. Also, I don't know how to code the "quit" option. Any advice would be greatly appreciated.
Thanks

PHP Code:

#include <stdio.h>

main()

{

int response;

 char *lname[20]={'\0'};
 char *fname[20]={'\0'};
 int  *id={'\0'};
 int  *gpa={'\0'};

  FILE *pWrite;
  FILE *pRead;


 printf("\n\tStudent Files\n");
 printf("\n1\tEnter Student Information\n");
 printf("\n2\tPrint Student Information\n");
 printf("\n3\tQuit\n");

 printf("Select an option: ");
 scanf("%d", &response);

  if (response==1) {
    
    printf("\nEnter first name: ");
    scanf("%s", fname);
    printf("\nEnter last name: ");
    scanf("%s", lname);
    printf("\nEnter student GPA: ");
    scanf("%d", &gpa);
    printf("\nEnter student id: ");
    scanf("%d", &id);

  pWrite=fopen("student_files.dat", "a");

   if (pWrite!=NULL) {

    fprintf(pWrite, "%s %s %d %d\n", fname, lname, gpa, id);
    fclose(pWrite);
  }

  else
   
     printf("\nFile cannot be opened\n");

  }

 if (response==2) {
   
   pRead=fopen("student_files.dat", "r");

   if (pRead!=NULL)  {
   printf("\nStudent Files\n");

     while (!feof(pRead) ) {
       fscanf(pRead, "%s %s %d %d", fname, lname, gpa, id);
  
     if ( !feof(pRead) )
      printf("\n%s %s\t%d\t%d", fname, lname, gpa, id);
  } //end loop
  
 
 printf("\n");
    

  }
  else
      printf("\nFile not opened\n");

   }
  else
    printf("\nInvalid Selection\n");
} 


[redhead]

In this case I would've used a switch statement ie:

while(1){
    printf("\n\tStudent Files\n"); 
    printf("\n1\tEnter Student Information\n"); 
    printf("\n2\tPrint Student Information\n"); 
    printf("\n3\tQuit\n"); 

    printf("Select an option: "); 
    response = getchar() - '0';
    switch(response){
        case 1:
            printf("\nEnter first name: "); 
            ...
            break;
         case 2:
            pRead=fopen("student_files.dat", "r");
            ...
            break;
         case 3:
            printf("Exiting\n");
            return 0;
         default:
            printf("\nInvalid Selection\n");
    }
}

For your fscanf(stdin, "%d", &some_var); you might want to use the %f conversion, and find it produces better results.

For an exit check, just extend your if() checks, but as I mintioned earlier, for this I would rather use some form of switch() clause.

if(response == 3)
{
    printf("Exiting\n");
    return 0;
}