Binary File Update

import pickle

def update_record():
    try:
        # Read all records
        records = []
        with open('student.dat', 'rb') as file:
            try:
                while True:
                    record = pickle.load(file)
                    records.append(record)
            except EOFError:
                pass
        
        if not records:
            print("No records found!")
            return
        
        # Search for record to update
        roll_to_update = int(input("Enter roll number to update: "))
        found = False
        
        for i, record in enumerate(records):
            if record['roll'] == roll_to_update:
                print(f"Current record:")
                print(f"Name: {record['name']}")
                print(f"Roll: {record['roll']}")
                print(f"Marks: {record['marks']}")
                
                # Update fields
                new_name = input("Enter new name (or press Enter to keep current): ")
                new_marks = input("Enter new marks (or press Enter to keep current): ")
                
                if new_name:
                    records[i]['name'] = new_name
                if new_marks:
                    records[i]['marks'] = int(new_marks)
                
                found = True
                break
        
        if not found:
            print("Record not found!")
            return
        
        # Write updated records back to file
        with open('student.dat', 'wb') as file:
            for record in records:
                pickle.dump(record, file)
        
        print("Record updated successfully!")
        
    except FileNotFoundError:
        print("File not found!")
    except Exception as e:
        print(f"Error: {e}")

def display_records():
    try:
        with open('student.dat', 'rb') as file:
            print("All Records:")
            print("=" * 30)
            try:
                while True:
                    record = pickle.load(file)
                    print(f"Name: {record['name']}")
                    print(f"Roll: {record['roll']}")
                    print(f"Marks: {record['marks']}")
                    print("-" * 20)
            except EOFError:
                pass
    except FileNotFoundError:
        print("File not found!")

# Main program
if __name__ == "__main__":
    choice = input("1. Update record\n2. Display records\nEnter choice: ")
    if choice == '1':
        update_record()
    elif choice == '2':
        display_records()
    else:
        print("Invalid choice!")