英文:
cs50 reflect code is failing. values are not in there right place
问题
我找不到解决这两个错误的方法，尽管当我自己测试时，图片反映得很正确。
这是错误信息：
使用1x3图片进行测试
第一行：(255, 0, 0), (0, 255, 0), (0, 0, 255)
运行 ./testing 2 1...
检查输出是否为 "0 0 255\n0 255 0\n255 0 0\n"...
期望输出：
0 0 255
0 255 0
255 0 0
实际输出：
0 0 0
0 0 255
0 255 0
我注意到第一行中有来自第二行的一个值，第二行中有来自第三行的一个值。
这是代码：
void reflect(int height, int width, RGBTRIPLE image[height][width])
{
//这是反映后的图像
RGBTRIPLE reflected[height][width];
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
reflected[h][w] = image[h][width - w];
}
}
//从反映的图像复制到原图像
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
image[h][w] = reflected[h][w];
}
}
return;
}
问题已解决，但现在我在3x3图像中遇到了另一个问题，每列的第一行都是零
期望输出：
255 0 0
255 0 0
255 0 0
0 255 0
0 255 0
0 255 0
0 0 255
0 0 255
0 0 255
实际输出：
0 0 0
255 0 0
255 0 0
0 0 0
0 255 0
0 255 0
0 0 0
0 0 255
0 0 255
尝试以不同方式编写代码，但最终仍然遇到了相同的错误。
英文:
I cant find a way to fix these two errors despite that the pic reflects correctly when i test it by myself.
this is the error
testing with sample 1x3 image
first row: (255, 0, 0), (0, 255, 0), (0, 0, 255)
running ./testing 2 1...
checking for output "0 0 255\n0 255 0\n255 0 0\n"...
Expected Output:
0 0 255
0 255 0
255 0 0
Actual Output:
0 0 0
0 0 255
0 255 0
I noticed that there is a value from the second row in the first row and a value from the third row in the second row.
this is the code:
void reflect(int height, int width, RGBTRIPLE image[height][width])
{
//this is where the reflected image gonna be
RGBTRIPLE reflected[height][width];
for (int h = 0 ; h < height ; h++)
{
for (int w = 0 ; w < width ; w++)
{
reflected[h][w] = image[h][width - w];
}
}
//copying from the reflected to the image
for (int h = 0 ; h < height ; h++)
{
for (int w = 0 ; w < width ; w++)
{
image[h][w] = reflected[h][w];
}
}
return;
}
the problem is solved but now I have another problem in 3x3 image where the first row of each column is zeros
Expected Output:
255 0 0
255 0 0
255 0 0
0 255 0
0 255 0
0 255 0
0 0 255
0 0 255
0 0 255
Actual Output:
0 0 0
255 0 0
255 0 0
0 0 0
0 255 0
0 255 0
0 0 0
0 0 255
0 0 255
tried writing the code in different ways but I ended up with the same bug.
答案1
得分: 1
你必须始终检查你的范围：image[r][c] 假定 0 <= r < height 且 0 <= c < width。
现在考虑你的 image[h][width-w]。width-w 的范围是多少？当 w = 0 => width-w = width。超出范围（并且是未定义的行为）。
你只需使用 image[h][width-1 - w] 来修复它。
英文:
You must always check your ranges: image[r][c] assumes that 0 <= r < height and that 0 <= c < width.
Now consider your image[h][width-w]. What is the range of width-w? When w = 0 => width-w = width. Out of range (and UB).
You just fix it with image[h][width-1 - w].
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