someone help me

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
using namespace std;
unsigned char* ReadBMP()
{
    FILE* f = fopen("testbnp.bmp", "rb");
    if (f == NULL)
        throw "Argument Exception";
    unsigned char info[54];
    fread(info, sizeof(unsigned char), 54, f);
    int width = *(int*)&info[18];
    int height = *(int*)&info[22];
    //cout << "Width: " << width << endl;
    //cout << "Height: " << height << endl;
    int w = width, h = height;
    int row_padded = (width * 3 + 3) & (~3);
    unsigned char** datapi = new unsigned char* [h];
    for (int i = 0; i < height; ++i) {
        datapi[i] = new unsigned char[row_padded];
    }
    unsigned char** textpi = new unsigned char* [h];
    for (int i = 0; i < height; ++i) {
        textpi[i] = new unsigned char[row_padded/3];
    }
    FILE* a;
    a = fopen("atest.txt", "wb");
    string asci = "##@%=+/*:-.,`";
    int len = asci.length();
    unsigned char* text = new unsigned char[row_padded];
    //cout << endl << row_padded;
    unsigned char* data = new unsigned char[row_padded];
    for (int i = 0; i < height; ++i) {
        fread(data, sizeof(unsigned char), row_padded, f);
        for (int j = 0; j < row_padded; j++) {
            datapi[i][j] = data[j];
        }
        for (int k = 0; k < row_padded; k += 3) {
            int temp = (int)datapi[i][k] * 0.114 + (int)datapi[i][k + 1] * 0.587 + (int)datapi[i][k + 2] * 0.229;
            datapi[i][k] = (unsigned char)temp;
            datapi[i][k + 1] = (unsigned char)temp;
            datapi[i][k + 2] = (unsigned char)temp;
            text[k] = asci[ceil(((len - 1) * temp) / 255)];
        }
        int b = 0;
        for (int j = 0; j < row_padded; j+=3, b++) {
            textpi[h - i - 1][b] = text[j];
        }
        //0.299R + 0.587G + 0.114B
    }


    for (int i = 0; i < h; ++i) {
        fwrite(textpi[i], 1, row_padded/3, a);
        fputc('\n', a);
    }
    unsigned char bmpfileheader[14] = { 'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0 };
    unsigned char bmpinfoheader[40] = { 40,0,0,0, 0,0,0,0, 0,0,0,0, 1,0, 24,0 };
    int filesize = 3 * w * h + 54;
    bmpfileheader[2] = (unsigned char)(filesize);
    bmpfileheader[3] = (unsigned char)(filesize >> 8);
    bmpfileheader[4] = (unsigned char)(filesize >> 16);
    bmpfileheader[5] = (unsigned char)(filesize >> 24);
    int temp1 = *(int*)&info[10];
    bmpfileheader[10] = (unsigned char)(temp1);
    bmpfileheader[11] = (unsigned char)(temp1 >> 8);
    bmpfileheader[12] = (unsigned char)(temp1 >> 16);
    bmpfileheader[13] = (unsigned char)(temp1 >> 24);
    bmpinfoheader[4] = (unsigned char)(w);
    bmpinfoheader[5] = (unsigned char)(w >> 8);
    bmpinfoheader[6] = (unsigned char)(w >> 16);
    bmpinfoheader[7] = (unsigned char)(w >> 24);
    bmpinfoheader[8] = (unsigned char)(h);
    bmpinfoheader[9] = (unsigned char)(h >> 8);
    bmpinfoheader[10] = (unsigned char)(h >> 16);
    bmpinfoheader[11] = (unsigned char)(h >> 24);

    FILE* l;
    l = fopen("img.bmp", "wb");
    fwrite(bmpfileheader, 1, 14, l);
    fwrite(bmpinfoheader, 1, 40, l);
    for (int i = 0; i < h; i++)
    {
        fwrite(datapi[i], 1, row_padded, l);
    }
    fclose(l);
    for (int i = 0; i < height; i++) {
        delete[] datapi[i];
    }
    delete[] datapi;
    delete[] data;
    delete[] text;
    fclose(f);
    fclose(a);
    return info;
}
int main(int argc, char* argv[])
{
    unsigned char* data = ReadBMP();
    cout << "done";
    return 0;
}