C++(Visual Studio)，不能写数字'10'要归档，所有其他号码都有效吗? [英] C++ (Visual Studio), Can't write the number '10' to file, all other numbers working?
问题描述
我这里有一个奇怪的问题！我正在尝试为 8 位 windows 3.x 位图文件编写颜色表.我只希望文件是灰度的，所以我想写 bbb0、ggg0、rrr0 256 次，其中 r=g=b=1..256
I have a bit of a weird problem here! I am trying to write the color table for a 8 bit windows 3.x bitmap file. I just want the file to be greyscale, so i am trying to write bbb0, ggg0, rrr0 256 times where r=g=b=1..256
//write greyscale color table
for (int i = 255; i >= 0; i--) {
writeS = (unsigned short)i;
outfile.write ((char*)&writeS,sizeof(char)); // b
outfile.write ((char*)&writeS,sizeof(char)); // g
outfile.write ((char*)&writeS,sizeof(char)); // r
writeS = 0;
outfile.write ((char*)&writeS,sizeof(char)); // 0
}
当我使用十六进制编辑器查看输出时，一切看起来都很好，直到我看到数字 10，它是这样写的:
When I look at the output i am getting with a hex editor, everything looks fine until I get to the number 10, which is written like so:
...0C 0C 0C 00 0B 0B 0B 00 0D 0A 0D 0A 0D 0A 00 09 09 09 00 08 08 08 00...
...0C 0C 0C 00 0B 0B 0B 00 0D 0A 0D 0A 0D 0A 00 09 09 09 00 08 08 08 00...
不是:
...0C 0C 0C 00 0B 0B 0B 00 0A 0A 0A 00 09 09 09 00 08 08 08 00...
...0C 0C 0C 00 0B 0B 0B 00 0A 0A 0A 00 09 09 09 00 08 08 08 00...
奇怪的是，它只对这个数字执行此操作，但更奇怪的是，当我更改代码以跳过数字 10 并改为写入 9 时，它可以工作.
So that is wierd that it is only doing it on this one number, but what is even wierder is that when I change the code to skip the number 10 and write 9 instead, it works.
//write greyscale color table
for (int i = 255; i >= 0; i--) {
writeS = (unsigned short)i;
if (writeS == 10) writeS = 9;
outfile.write ((char*)&writeS,sizeof(char)); // b
outfile.write ((char*)&writeS,sizeof(char)); // g
outfile.write ((char*)&writeS,sizeof(char)); // r
writeS = 0;
outfile.write ((char*)&writeS,sizeof(char)); // 0
}
给出:
...0C 0C 0C 00 0B 0B 0B 00 09 09 09 00 09 09 09 00 08 08 08 00...
...0C 0C 0C 00 0B 0B 0B 00 09 09 09 00 09 09 09 00 08 08 08 00...
符号有什么奇怪的地方吗?我错过了任何明显的错误?有没有人遇到过这样的事情?谢谢！
Is there something weird going on there with notation? Any obvious errors that I have missed? Has anyone ran into something like this before? Thanks!
推荐答案
ASCII 中的数字 10"是换行符，\n.在 C++ 中，这是换行符.
The "number 10" in ASCII is the line feed character, \n. In C++, this is the newline character.
您显然已将文件作为文本流打开.由于换行在不同平台上的表示方式不同，文本流执行换行转换:读取时将特定于平台的换行表示转换为 \n，写入时将\n字符转换为特定于平台的换行符.
You have apparently opened the file as a text stream. Because newlines are represented differently on different platforms, text streams perform newline translation: when reading they translate the platform-specific newline representation into \n and when writing they translate the \n character into the platform-specific newline representation.
在 Windows 上，换行符由 \r\n 表示.当您将 \n 写入文本流时，它会被写入为 \r\n.
On Windows, line breaks are represented by \r\n. When you write a \n to the text stream, it gets written as \r\n.
要写入原始二进制数据，您需要将流作为二进制流打开.这是通过将 ios_base::binary 标志传递给流的构造函数来完成的.
To write raw binary data, you need to open the stream as a binary stream. This is done by passing the ios_base::binary flag to the constructor of the stream.
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