我有一个VB的程序需要调用一个DLL以实现某一简单图像处理功能。我因为C++不熟，就用C编了这么一个程序（主要是文件读入，输出及数组操作）。但现在需要在VC++的环境下将这个C程序，编译为DLL，请问需要做那些改动？另外，参数如何传递（DLL需要从VB得到两个整型变量参数，返回一个整型变量参数）？C的那段程序大体如下：#include <stdio.h>
#include <stdlib.h>
#include <math.h>void main()
{
FILE *raw_map,*out_map;
int y,x,j,i,m,n; int gps_y,gps_x;
int long1_x,long2_x,lat1_y,lat2_y;
int long_x[9],lat_y[9];
int var_x,var_y;
int num_written; unsigned char pixels[450][450];
unsigned char domain[150][150];
// read-in campus.bmp is an image of 450x450
raw_map = fopen("campus.raw","rb");
for(y = 0; y < 450; y++)
for(x = 0; x < 450; x++)
pixels[y][x] = fgetc(raw_map);
fclose(raw_map); long1_x = 5000, lat1_y = 2027;
long2_x = 5081, lat2_y = 2000; gps_x = 5030, gps_y = 2011; // These two var should be
// passed from VB program // coordinazied map area into ranges
var_x = (long2_x - long1_x)/9;
var_y = (lat1_y - lat2_y)/9; for (i=0;i<9;i++)
{
long_x[i] = long1_x + i*var_x;
lat_y[i] = lat1_y - i*var_y;
} // use gps data to locate the current range
m = 0, n = 0;
while (gps_x > long_x[m])
{
m = m + 1;
}
while (gps_y < lat_y[n])
{
n = n + 1;
} // m,n is the coordinates of current range num_written = m + n;
return num_written;
}这也不是程序的全部，大抵是这样，有些地方还需要修改，请大虾指教如何把这一C的程序转换成DLL？
#include <stdlib.h>
#include <math.h>void main()
{
FILE *raw_map,*out_map;
int y,x,j,i,m,n; int gps_y,gps_x;
int long1_x,long2_x,lat1_y,lat2_y;
int long_x[9],lat_y[9];
int var_x,var_y;
int num_written; unsigned char pixels[450][450];
unsigned char domain[150][150];
// read-in campus.bmp is an image of 450x450
raw_map = fopen("campus.raw","rb");
for(y = 0; y < 450; y++)
for(x = 0; x < 450; x++)
pixels[y][x] = fgetc(raw_map);
fclose(raw_map); long1_x = 5000, lat1_y = 2027;
long2_x = 5081, lat2_y = 2000; gps_x = 5030, gps_y = 2011; // These two var should be
// passed from VB program // coordinazied map area into ranges
var_x = (long2_x - long1_x)/9;
var_y = (lat1_y - lat2_y)/9; for (i=0;i<9;i++)
{
long_x[i] = long1_x + i*var_x;
lat_y[i] = lat1_y - i*var_y;
} // use gps data to locate the current range
m = 0, n = 0;
while (gps_x > long_x[m])
{
m = m + 1;
}
while (gps_y < lat_y[n])
{
n = n + 1;
} // m,n is the coordinates of current range num_written = m + n;
return num_written;
}这也不是程序的全部，大抵是这样，有些地方还需要修改，请大虾指教如何把这一C的程序转换成DLL？
用_declspec(dllimport)声明一个函数就可以输入之
选择vc的新工程，选择win32 dll，按照所有的步骤选择一个输出简单函数的例子，
之后看看援文件你就明白了
我本来以为c不能写dll的。没有相关的库函数。因为dll是windows的概念。
看来借着vc的帮助倒是可以。