Memory & arrays - Memory Leak help

#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
#include <stdio.h>
#include <string.h>

typedef struct
{
	char* firstname;
	char* lastname;
	int id;
	float mark;
}StudentRecord;

StudentRecord* g_pRecords;
int g_numRecords = 0;
char* g_FileName;
FILE* g_pf;
typedef enum{FALSE,TRUE}BOOL;

void OpenFile(void);
void ListRecords(void);
void AddRecord(void);
void DeleteRecord(void);
void SaveRecords(void);

int main()
{
	BOOL running = TRUE;
	char response;

	OpenFile();

	while(running)
	{
		printf(
			"1. List records in memory\n"
			"2. Add a new record\n"
			"3. Delete last record\n"
			"4. Quit and Save records to file\n"
			);

		fflush(stdin);
		scanf("%c",&response);

		switch(response)
		{
		case '1':
			ListRecords();
			break;
		case '2':
			AddRecord();
			break;
		case '3':
			DeleteRecord();
			break;
		case '4':
			running = FALSE;
			SaveRecords();
			break;
		default: printf("Invalid Choice\n");
		}
	}
	return 0;
}


void OpenFile(void){
	
	int n_count = 0;
	int n_id = 0;
	char c_filename[30];
	float f_mark = 0.0;
	char c_fName[32];
	char c_lName[32];

	printf("OPEN FILE\nPlease enter the name of the file to open: ");
	fflush(stdin);
	scanf("%s",c_filename);

	g_FileName = (char *)malloc(((int)(strlen(c_filename)+1)));
	strcpy(g_FileName, c_filename);

	g_pRecords = (StudentRecord *)malloc(g_numRecords * sizeof(StudentRecord));

	if((g_pf = fopen(g_FileName, "r" )) != NULL && fgetc(g_pf) != EOF){
		rewind(g_pf);
		
		while(fscanf(g_pf, "%32s %32s %d %f\n", c_fName, c_lName, &n_id, &f_mark) != EOF){

			g_pRecords[n_count].firstname = (char *)malloc(((int)strlen(c_fName)+1));
			strcpy(g_pRecords[n_count].firstname, c_fName);
			g_pRecords[n_count].lastname = (char *)malloc(((int)strlen(c_lName)+1));
			strcpy(g_pRecords[n_count].lastname, c_lName);
			g_pRecords[n_count].id = n_id;
			g_pRecords[n_count].mark = f_mark;

			n_count++;
			
		}
		g_numRecords = n_count;
		printf("Records Added: %d\n", g_numRecords);
	}else{
		g_numRecords = 0;
		printf("Empty File\n");
	}

	fclose(g_pf);
	if(g_numRecords == 0)
		free(g_pRecords);
}


void ListRecords(void){

	int n_Records = 0;
	printf("LIST RECORDS IN MEMORY\n");
	
	if(g_numRecords >= 0){		
		for(n_Records = 0; n_Records < g_numRecords; n_Records++){
			printf("Record #%d\n", n_Records+1);
			printf("First name = %s\n", g_pRecords[n_Records].firstname);
			printf("Last Name = %s\n", g_pRecords[n_Records].lastname);
			printf("ID = %d\n", g_pRecords[n_Records].id);
			printf("Mark = %5.2f\n", g_pRecords[n_Records].mark);
			printf("\n");
		}			
	}else
		printf("No records\n");
}

void AddRecord(void){

	int n_count = 0;
	char c_fName[32];
	char c_lName[32];

	for(n_count = 0; n_count <= g_numRecords; n_count++){

		if(n_count == g_numRecords){
	
			printf("Please enter First Name: ");
			fflush(stdin);
			scanf("%s", c_fName, (int)(strlen(c_fName)+1), stdin);
				g_pRecords[n_count].firstname = (char *)malloc((int)(strlen(c_fName)+1));
				strcpy(g_pRecords[n_count].firstname, c_fName);
			printf("Please enter Last Name: ");
			fflush(stdin);
			scanf("%s", c_lName, (int)(strlen(c_lName)+1), stdin);
				g_pRecords[n_count].lastname = (char *)malloc((int)(strlen(c_lName)+1));
				strcpy(g_pRecords[n_count].lastname, c_lName);
			printf("Please enter ID: ");
			fflush(stdin);
			scanf("%d", &g_pRecords[n_count].id);
			printf("Please enter mark: ");
			fflush(stdin);
			scanf("%f", &g_pRecords[n_count].mark);
		}
	}	
	g_numRecords++;
	printf("Number of Records = %d\n", g_numRecords,
		"ADDED A NEW RECORD TO MEMORY OK");
}

void DeleteRecord(void){

	int n_count = 0;
	StudentRecord *pt_tmpRecords;

	pt_tmpRecords = (StudentRecord *)malloc(sizeof(StudentRecord)*g_numRecords);

	for(n_count = 0; n_count < g_numRecords; n_count++){
		pt_tmpRecords[n_count].firstname = (char *)malloc((int)(strlen(g_pRecords[n_count].firstname)+1));
		strcpy(pt_tmpRecords[n_count].firstname , g_pRecords[n_count].firstname);
		pt_tmpRecords[n_count].lastname = (char *)malloc((int)(strlen(g_pRecords[n_count].lastname )+1));
		strcpy(pt_tmpRecords[n_count].lastname, g_pRecords[n_count].lastname);
		pt_tmpRecords[n_count].id = g_pRecords[n_count].id;
		pt_tmpRecords[n_count].mark = g_pRecords[n_count].mark;
	}
	for(n_count = 0; n_count < g_numRecords; n_count++){
		free(g_pRecords[n_count].firstname);
		free(g_pRecords[n_count].lastname);
	}
	g_numRecords--; 
	

	for(n_count = 0; n_count < g_numRecords; n_count++){
		g_pRecords[n_count].firstname = (char *)malloc((int)(strlen(pt_tmpRecords[n_count].firstname)+1));
		strcpy(g_pRecords[n_count].firstname , pt_tmpRecords[n_count].firstname);
		g_pRecords[n_count].lastname = (char *)malloc((int)(strlen(pt_tmpRecords[n_count].lastname)+1));
		strcpy(g_pRecords[n_count].lastname, pt_tmpRecords[n_count].lastname);
		g_pRecords[n_count].id = pt_tmpRecords[n_count].id;
		g_pRecords[n_count].mark = pt_tmpRecords[n_count].mark;
	}
	
	for(n_count = 0; n_count < g_numRecords+1; n_count++){
		free(pt_tmpRecords[n_count].firstname);
		free(pt_tmpRecords[n_count].lastname);
	}
	free(pt_tmpRecords);
	
	printf("\nDELETED LAST RECORD IN MEMORY OK\n");
}

void SaveRecords(void){

	int n_count = 0;

	if((g_pf = fopen(g_FileName, "w+" )) != NULL){
		for(n_count = 0; n_count < g_numRecords; n_count++){
			fprintf(g_pf, "%s %s %d %5.2f\n",
				g_pRecords[n_count].firstname,
				g_pRecords[n_count].lastname,
				g_pRecords[n_count].id,
				g_pRecords[n_count].mark);
		}
	}
	fclose(g_pf);

	g_numRecords--;
	while(g_numRecords >= 0){
		free(g_pRecords[g_numRecords].firstname);
		free(g_pRecords[g_numRecords].lastname);
		g_numRecords--;
	}

	free(g_FileName);
	_CrtDumpMemoryLeaks();
	exit(EXIT_SUCCESS);
}