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Aug 22nd, 2008

how to read a binary file data to a monitor

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Please compare the two codes below why is the first one displaying output to monitor where as the second code is displaying some unwanted characters.

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C++ Syntax (Toggle Plain Text)
CODE 1 .....
#include <fstream.h>
#include <string.h>
 
void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );
 
	char arr[13];
	strcpy(arr,"Hello World!"); //put Hello World! into the array
 
	File.write(arr,5); //put the first 5 symbols into the file- "Hello"
 
	static char read_array[10]; //I will put the read data, here
 
	File.seekg(ios::beg);
	File.read(read_array,5); //read the first 3 symbols- "Hel"
 
	cout << read_array << endl; //display them
 
	File.close();
}
 
CODE 2....
#include <fstream.h>
#include <string.h>
 
void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );
	char * memblock;
	ifstream::pos_type size;
	//int size;
 
	File.seekg(ios::ate);
	size = File.tellg();
	memblock = new char[size];
	File.read(memblock,size);
 
	//cout<<*memblock;
	//cout<<"\n";
	cout<<memblock;
 
	File.close();
}
CODE 1 .....
#include <fstream.h>
#include <string.h>

void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );

	char arr[13];
	strcpy(arr,"Hello World!"); //put Hello World! into the array

	File.write(arr,5); //put the first 5 symbols into the file- "Hello"

	static char read_array[10]; //I will put the read data, here

	File.seekg(ios::beg);
	File.read(read_array,5); //read the first 3 symbols- "Hel"

	cout << read_array << endl; //display them

	File.close();
}

CODE 2....
#include <fstream.h>
#include <string.h>

void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );
	char * memblock;
	ifstream::pos_type size;
	//int size;

	File.seekg(ios::ate);
	size = File.tellg();
	memblock = new char[size];
	File.read(memblock,size);

	//cout<<*memblock;
	//cout<<"\n";
	cout<<memblock;
	
	File.close();
}
    C++ Syntax (Toggle Plain Text)  CODE 1 .....#include <fstream.h>#include <string.h> void main(){	fstream File("test_file.txt",ios::out | ios::in | ios::binary ); 	char arr[13];	strcpy(arr,"Hello World!"); //put Hello World! into the array 	File.write(arr,5); //put the first 5 symbols into the file- "Hello" 	static char read_array[10]; //I will put the read data, here 	File.seekg(ios::beg);	File.read(read_array,5); //read the first 3 symbols- "Hel" 	cout << read_array << endl; //display them 	File.close();} CODE 2....#include <fstream.h>#include <string.h> void main(){	fstream File("test_file.txt",ios::out | ios::in | ios::binary );	char * memblock;	ifstream::pos_type size;	//int size; 	File.seekg(ios::ate);	size = File.tellg();	memblock = new char[size];	File.read(memblock,size); 	//cout<<*memblock;	//cout<<"\n";	cout<<memblock; 	File.close();} CODE 1 .....
#include <fstream.h>
#include <string.h>

void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );

	char arr[13];
	strcpy(arr,"Hello World!"); //put Hello World! into the array

	File.write(arr,5); //put the first 5 symbols into the file- "Hello"

	static char read_array[10]; //I will put the read data, here

	File.seekg(ios::beg);
	File.read(read_array,5); //read the first 3 symbols- "Hel"

	cout << read_array << endl; //display them

	File.close();
}

CODE 2....
#include <fstream.h>
#include <string.h>

void main()
{
	fstream File("test_file.txt",ios::out | ios::in | ios::binary );
	char * memblock;
	ifstream::pos_type size;
	//int size;

	File.seekg(ios::ate);
	size = File.tellg();
	memblock = new char[size];
	File.read(memblock,size);

	//cout<<*memblock;
	//cout<<"\n";
	cout<<memblock;
	
	File.close();
} 

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mksakeesh

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Aug 22nd, 2008

Re: how to read a binary file data to a monitor

CODE 1 may end in problems, too, because of the missing terminating 0 in read_array

CODE 2 is missing a rewind to begin of file before File.read(memblock,size); and has the same problem with the terminating 0. Replace memblock = new char[size]; by memblock = new char[size + 1]; memblock[size] = 0;

Last edited by jencas; Aug 22nd, 2008 at 11:27 am.

jencas

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Aug 22nd, 2008

Re: how to read a binary file data to a monitor

You would also need to delete the memory you've freed, or else you'll get a memory leak

Nick Evan

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Aug 22nd, 2008

Re: how to read a binary file data to a monitor

Both suffer from having void main as well.

Salem

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This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

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