C++ 写入PGM文件
我正在尝试使用此代码编写pgm文件C++ 写入PGM文件,c++,pgm,C++,Pgm,我正在尝试使用此代码编写pgm文件 myfile << "P5" << endl; myfile << sizeColumn << " " << sizeRow << endl; myfile << Q << endl; myfile.write( reinterpret_cast<char *>(image), (sizeRow*sizeColumn)*sizeof(unsigne
myfile << "P5" << endl;
myfile << sizeColumn << " " << sizeRow << endl;
myfile << Q << endl;
myfile.write( reinterpret_cast<char *>(image), (sizeRow*sizeColumn)*sizeof(unsigned char));
myfile确保使用ios::binary
标志以二进制模式打开文件。如果您使用的是Windows,则可能需要将endl
替换为“\r\n”
。您可能不想使用,因为它会刷新输出流
此外,如果您希望与Windows(可能还有来自Microsoft的任何其他操作系统)兼容,则必须以二进制模式打开该文件。默认情况下,Microsoft以文本模式打开文件,这通常有一个不兼容的功能(古老的DOS向后兼容),没有人想要了:它将每个“\n”替换为“\r\n”
PGM文件格式标头为:
"P5" + at least one whitespace (\n, \r, \t, space)
width (ascii decimal) + at least one whitespace (\n, \r, \t, space)
height (ascii decimal) + at least one whitespace (\n, \r, \t, space)
max gray value (ascii decimal) + EXACTLY ONE whitespace (\n, \r, \t, space)
这是一个将pgm输出到文件的示例:
#include <fstream>
const unsigned char* bitmap[MAXHEIGHT] = …;// pointers to each pixel row
{
std::ofstream f("test.pgm",std::ios_base::out
|std::ios_base::binary
|std::ios_base::trunc
);
int maxColorValue = 255;
f << "P5\n" << width << " " << height << "\n" << maxColorValue << "\n";
// std::endl == "\n" + std::flush
// we do not want std::flush here.
for(int i=0;i<height;++i)
f.write( reinterpret_cast<const char*>(bitmap[i]), width );
if(wannaFlush)
f << std::flush;
} // block scope closes file, which flushes anyway.
#包括
常量无符号字符*位图[MAXHEIGHT]=…;//指向每个像素行的指针
{
流f的std::of(“test.pgm”,std::ios_base::out
|std::ios_base::binary
|std::ios_base::trunc
);
int maxColorValue=255;
f是你没有工作的东西?如果是,怎么做?