使用c语言写一个能让bmp位图旋转给定角度的程序，bmp位图命名为data.bmp，旋转后的图像命名为datar.bmp

好的，以下是一个使用C语言编写的程序，可以将给定角度的BMP位图旋转，并将旋转后的图像保存为datar.bmp。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

typedef struct {
    unsigned char blue;
    unsigned char green;
    unsigned char red;
} Pixel;

typedef struct {
    int width;
    int height;
    Pixel *data;
} Image;

void rotateImage(Image *src, Image *dst, double angle) {
    double radian = angle * M_PI / 180.0;
    double cosValue = cos(radian);
    double sinValue = sin(radian);
    int cx = src->width / 2;
    int cy = src->height / 2;

    for (int y = 0; y < dst->height; y++) {
        for (int x = 0; x < dst->width; x++) {
            int srcX = (int)(cosValue * (x - cx) + sinValue * (y - cy) + cx);
            int srcY = (int)(-sinValue * (x - cx) + cosValue * (y - cy) + cy);

            if (srcX >= 0 && srcX < src->width && srcY >= 0 && srcY < src->height) {
                int dstIndex = y * dst->width + x;
                int srcIndex = srcY * src->width + srcX;

                dst->data[dstIndex] = src->data[srcIndex];
            }
        }
    }
}

Image *readBmp(const char *filename) {
    FILE *file = fopen(filename, "rb");
    if (!file) {
        printf("Error: Failed to open file '%s'\n", filename);
        return NULL;
    }

    unsigned char header[54];
    if (fread(header, sizeof(unsigned char), 54, file) != 54) {
        printf("Error: Invalid BMP file\n");
        fclose(file);
        return NULL;
    }

    int width = *(int*)&header[18];
    int height = *(int*)&header[22];
    int dataSize = *(int*)&header[34];

    if (dataSize == 0) {
        dataSize = width * height * 3;
    }

    unsigned char *data = (unsigned char*)malloc(dataSize);
    if (!data) {
        printf("Error: Failed to allocate memory for image data\n");
        fclose(file);
        return NULL;
    }

    fread(data, sizeof(unsigned char), dataSize, file);
    fclose(file);

    Image *image = (Image*)malloc(sizeof(Image));
    image->width = width;
    image->height = height;
    image->data = (Pixel*)malloc(width * height * sizeof(Pixel));

    int dataIndex = 0;
    for (int i = 0; i < width * height; i++) {
        image->data[i].blue = data[dataIndex++];
        image->data[i].green = data[dataIndex++];
        image->data[i].red = data[dataIndex++];
    }

    free(data);

    return image;
}

void writeBmp(const char *filename, Image *image) {
    unsigned char header[54] = {
        'B', 'M', 0, 0, 0, 0, 0, 0, 0, 0, 54, 0, 0, 0, 40, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 1, 0, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };

    *(int*)&header[18] = image->width;
    *(int*)&header[22] = image->height;
    *(int*)&header[34] = image->width * image->height * sizeof(Pixel);

    FILE *file = fopen(filename, "wb");
    if (!file) {
        printf("Error: Failed to create file '%s'\n", filename);
        return;
    }

    fwrite(header, sizeof(unsigned char), 54, file);
    for (int i = 0; i < image->width * image->height; i++) {
        fwrite(&image->data[i].blue, sizeof(unsigned char), 1, file);
        fwrite(&image->data[i].green, sizeof(unsigned char), 1, file);
        fwrite(&image->data[i].red, sizeof(unsigned char), 1, file);
    }

    fclose(file);
}

int main() {
    const char *inputFilename = "data.bmp";
    const char *outputFilename = "datar.bmp";
    double rotationAngle = 45.0;

    Image *inputImage = readBmp(inputFilename);
    if (!inputImage) {
        return -1;
    }

    Image *outputImage = (Image*)malloc(sizeof(Image));
    outputImage->width = inputImage->width;
    outputImage->height = inputImage->height;
    outputImage->data = (Pixel*)malloc(inputImage->width * inputImage->height * sizeof(Pixel));

    rotateImage(inputImage, outputImage, rotationAngle);

    writeBmp(outputFilename, outputImage);

    free(inputImage->data);
    free(inputImage);
    free(outputImage->data);
    free(outputImage);

    return 0;
}

请将上述代码保存到一个名为 `bmp_rotation.c` 的文件中，并确保你已经有一个名为 `data.bmp` 的BMP图像文件放在同一目录下。然后，使用C编译器编译运行该程序，它将生成一个名为 `datar.bmp` 的旋转后的图像文件。

请注意，这个程序只支持24位颜色的BMP图像。如果你的图像是其他格式或是压缩过的，可能会出现问题。此外，该程序只能进行整数度数的旋转，如果需要更精确的旋转，你可能需要使用更高级的算法或库。