why my windows forms application is autoexiting in project?

private:
	void split_it()
	{
		FILE *fpi, *fpo;//file pointers for the input and output files respectively.
		char * dr = new char[1024];
		char inputfilename[100] = "", tmp[20] = ".part", tname[80] = "", c;
		int n = 2, j = 0, l = 0, m = 0, rem = 0;
		long divided = 0;
		double k = 0;
		n = int(No_of_Parts; Value);
		size_t size;

		for each (char t in Input_Path - > Text)
		{
			inputfilename[j] = t;
			j++;
		}

		j = 0;

		if ((fpi = fopen(inputfilename, "rb")) == NULL)
		{
			System::Windows::Forms::MessageBox::Show("Invalid File Name:");
			exit(0);
		}

		fseek(fpi, 0, SEEK_END);
		k = ftell(fpi);
		rewind(fpi);

		for (j = strlen(inputfilename); j> = 0; j--)
		{
			if (inputfilename[j] == '.')
			{
				for (m = j - 1; inputfilename[m] != '/'; m--)
				{
					tname[l] = inputfilename[m];
					l++;
				}
			}
		}
		strrev(tname);

		for (j = 0; j< n; j++)
		{
			c = j + '0';
			output[j].outputfiles = new char[20];
			strcpy(output[j].outputfiles, inputfilename);
			tmp[strlen(tmp)] = c;
			strcat(output[j].outputfiles, tmp);

			strcpy(tmp, ".part");
		}

		divided = long(k) / n;

		rem = long(k) - (divided*n);

		m = divided / 512;

		for (j = 0; j< (n - 1); j++)
		{
			l = 0;
			fpo = fopen(output[j].outputfiles, "wb+");

			while (l != m)
			{
				size = fread(dr, 1, 512, fpi);
				fwrite(dr, size, 1, fpo);
				l++;
			}

			m = divided - (m * 512);
			size = fread(dr, 1, m, fpi);
			fwrite(dr, size, 1, fpo);
			fclose(fpo);
			m = divided / 512;
		}

		l = 0;
		fpo = fopen(output[j].outputfiles, "wb+");

		while (l != m)
		{
			size = fread(dr, 1, 512, fpi);
			fwrite(dr, size, 1, fpo);
			l++;
		}

		m = divided - (m * 512);
		m = m + rem;
		size = fread(dr, 1, m, fpi);
		fwrite(dr, size, 1, fpo);
		fclose(fpi);
		fclose(fpo);

	}