i have a code here.. it has one error.. and i don't know what to do.. CAN YOU PLEASE HELP ME.. CAN YOU PLEASE REPAIR MY CODE... PLEAAAASSSEEE!!!

here's my code.. (it has only one error..)

<----------------------------->
Code:
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>

void initval();

int chars[255];

int main()
{
	FILE *file_r;
	int ferr = 0, i;
	char filename[50];
	while (ferr == 0)
	{
		system("cls");
		printf("Enter file name: ");
		gets(filename);
		file_r = fopen(filename, "r");
		if (file_r == 0)
		{
			printf("Error! File does not exist!");
			getch();
		}
		else
		{
			ferr = 1;
		}
	}
	char *r;
	char c, ctr = 0;

	while ((c = getc(file_r)) != EOF)
	{
		ctr++;
	}
	
	fclose(file_r);
	file_r = fopen(filename, "r");
	
	char string[ctr];
	
	i = -1;
	while ((c = getc(file_r)) != EOF)
	{
		i++;
		string[i] = c;
	}
	
	printf("\n%s", string);

	printf("\n\n%s\n\n", strrev(string));

	//tig-ihap

	for (i = 0; i < strlen(string); i++)
	{
		chars[string[i]]++;
	}
	
	for (i = 0; i < 256; i++)
	{
		if (chars[i] != 0)
		{
			printf("%c = %d\n", i, chars[i]);
		}
	}
	
	getch();
	
	fclose(file_r);
	return 0;
}

void initval()
{
	int i;
	for (i = 0; i < 256; i++)
	{
		chars[i] = 0;
	}
}