C++输出bmp图片的宽和高

在C++中，读取BMP图像文件的宽度和高度通常需要借助第三方库，因为标准库本身并不提供直接解析BMP的能力。libbmp、FreeImage库等都是常见的用于处理位图文件的选择。下面是一个简单的示例，使用FreeImage库来获取BMP图片的尺寸：

#include <freeimage.h>

bool isBmp(const char* filename) {
    return FreeImage_GetExtension(filename) == ".bmp";
}

void getBMPDimensions(const char* filename, int& width, int& height) {
    if (!isBmp(filename)) {
        throw std::runtime_error("Not a BMP file.");
    }

    FIBITMAP* dib = FreeImage_Load(filename);
    if (!dib) {
        throw std::runtime_error("Failed to load the image.");
    }
    
    width = FreeImage_GetWidth(dib);
    height = FreeImage_GetHeight(dib);

    FreeImage_Unload(dib); // Don't forget to release the memory after use
}

int main() {
    const char* bmpFile = "path_to_your_bmp_file.bmp";
    int width, height;
    try {
        getBMPDimensions(bmpFile, width, height);
        std::cout << "Width: " << width << ", Height: " << height << std::endl;
    } catch (const std::exception& e) {
        std::cerr << "Error: " << e.what() << std::endl;
    }
    return 0;
}