getting seg fault while reading from a binary file that is created by the same code

I have written this code to make a binary file of float numbers, but I get a segmentation fault error at the end. It writes 9000 float numbers to the file but when reading it only reads 4096 of them. When I run the executable file a few times the number of bytes it reads switches between 4096, 8192 and 9000. but I have seg fault always there...

float *realRef = new float [length];  //then filling it out...


ofstream out("blah.bin", ios::out | ios::binary);

out.write((char *) &realRef, length*sizeof(float)); 开发者_运维技巧 //length is 9000
out.close();    

ifstream in("blah.bin", ios::in | ios::binary);

float *readTest= new float[length];

in.seekg(0, ios::end);
size_t size=in.tellg();   // printing size shows 4096 BUT it should be 9000
in.seekg(0, ios::beg);

in.read((char *) &readTest, size);    
cout << in.gcount() << " bytes read." << endl;

in.close();

There is an error in your code. There is no need to take address of pointers.

//out.write((char *) &realRef, length*sizeof(float));
out.write((char *) realRef, length*sizeof(float));

//in.read((char *) &readTest, size);
in.read((char *) readTest, size);

Your Code updated:

out.write((char *) realRef, length*sizeof(float));  //length is 9000

in.read((char *) readTest, size);

You were passing address of pointer.

The segfault is because you read and write from the pointers themselves, not what is pointed to. Remove the & from the write and read statements.

It is also generally a good idea to check the value returned by write, to see how much was actually written.

There is an error in your first line:

float *realRef = new float [length];

new returns a pointer to the newly allocated memory. The array brackets are also translated to a pointer. So in effect you do

float* realRef = float**(malloc(...))

The right way to do this would be

float* realRef = float[length]