表达式必须是可修改的L值错误

Question

我正在编写一个读取ppm文件的代码，并将文件的宽度，高度和像素存储到图像对象中。在我的图像类中，我有一个包含图像数据的指针。我在设置x，y像素的rgb值的方法中也有错误。

 typedef load compontent_t 
 class Image
 {
 public:
 enum channel_t { RED = 0, GREEN, BLUE };          
 protected:
 component_t * buffer;                        //! Holds the image data.

 unsigned int width,             //! The width of the image (in pixels)
 height;                        //! The height of the image (in pixels)


// data mutators

/*! Sets the RGB values for an (x,y) pixel.
 *
 *  The method should perform any necessary bounds checking.
 *
 *  \param x is the (zero-based) horizontal index of the pixel to set.
 *  \param y is the (zero-based) vertical index of the pixel to set.
 *  \param value is the new color for the (x,y) pixel.
 */
 void setPixel(unsigned int x, unsigned int y, Color & value) {
 if (x > 0 && x < width && y > 0 && y < height) {
 size_t locpixel = y*width + x;
 size_t componentofpixel = locpixel * 3;
 *buffer + componentofpixel = value.r;
 *buffer + componentofpixel + 1 = value.g;
 *buffer + componentofpixel + 2 = value.b;    
  }
 else {
 cout << "Pixel out of bounds" << endl;
  }
 }


Image(unsigned int width, unsigned int height,  component_t * data_ptr): width(width), height(height),buffer(data_ptr) {}

所以在setPixel方法中，当我试图找到缓冲区的正确位置来设置rgb值时，它会向我显示错误：＆＃34;表达式必须是可修改的L值＆＃34;