check "fwrite" return value

[Adidas]

my code is

fwrite(Head , sizeof(Student) , 1 , dat)
How I check if my allocation succeeded/fail?

Thanks in advance 4 all of you :)

[hamsterman]

http://www.cplusplus.com/reference/clibrary/cstdio/fwrite/

Return Value
The total number of elements successfully written is returned as a size_t object, which is an integral data type.
If this number differs from the count parameter, it indicates an error.

[Adidas]

can you write it down in code please?

[anonymous23323124]

Check, using an if statement, if the size returned equals the number of elements, i.e. count parameter:

if (return_value != count)
{
   // an error

}

where, of course, you substitute for the italicised variables as appropriate, and add your error handling code inside the if block.

[Adidas]

I have a problam

fwrite(Head , sizeof(Student) , 1 , dat);	
if(size_t != count)
std::cout<<"The systerm did not succeeded saving your request"<<endl; 	
std::cout<<"The system absorbed your student"<<endl;	// check if the fwrite Succeed 

i'm getting an error "error C2059: syntax errer: '!="

what am I suppose to do ?

[anonymous23323124]

I'm sorry. Perhaps I was not very clear. You don't have a variable called count. It is the third parameter of the fwrite function, in your case 1.

Further, size_t is a data type, like int (well, in a manner of speaking...). You want to get the return value of fwrite:

size_t return_value = fwrite(Head, sizeof(Student), 1, dat);

Then use an if statement to compare this return value and the count parameter.

[Adidas]

You are the KING !
Thank you !

[anonymous23323124]

No problem. Do you now understand everything, and have your program working as you want it to?

[Adidas]

In fact yes, but I have another question...
The Visual studio created a binary file named data.dat (as I asked him to.. :) ) , can I take this file and open it in other program ?
I mean open a new project and load this "data.dat" ...?

[anonymous23323124]

It's just a binary text file right? Then yes, you can open it in another program. But remember that it must be read in exactly the same way.

But, it is possibly the case that such a file would be problematic on another computer, where the format in memory of your class Student might be different.