read from binary file and store to a buffer

Question

Can somebody tell if this is correct? I try to read from binary file line by line and store it in a buffer? does the new line that it stores in the buffer delete the previous stored line?

        ifs.open(filename, std::ios::binary);
        for (std::string line; getline(ifs, line,' '); )
                {
                    ifs.read(reinterpret_cast<char *> (buffer), 3*h*w);

                }

Starl1ght · Accepted Answer · 2016-12-01 10:55:11Z

1

For some reason you are mixing getline which is text-based reading, and read(), which is binary reading.

Also, it's completely unclear, what is buffer and what's it size. So, here is a simple example for you to start:

ifs.open(filename, std::ios::binary); // assume, that everything is OK

constexpr size_t bufSize = 256;
char buffer[bufSize];
size_t charsRead{ 0 };
do {
    charsRead = ifs.read(buffer, bufSize)
    // check if charsRead == 0, if it's ok
    // do something with filled buffer.
    // Note, that last read will have less than bufSize characters,
    // So, query charsRead each time.
} while (charsRead == bufSize);

answered Dec 1, 2016 at 10:55

Starl1ght

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2 Comments

madrugadas25845 Over a year ago

i have to read a ppm file and store it to a buffer. the size of the buffer has to be height*weight*3. So, do you think this method is fast for this? Thanks

Starl1ght Over a year ago

method is absolutely ok, you just need it to adjust it for your ppm

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