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Aug 19th, 2008

Need to write an integer to a binary file

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C++ Syntax (Toggle Plain Text)
#include<fstream.h>
#include<iostream.h>
#include<string.h>
using namespace std;
class emp
{
	public:
		char *per;
int i;
	int write2()
		{		
			ofstream out("ss.txt",ios::app | ios::binary );
 
			cout<<"Enter some character ....\n";
 
			per = new char[100];
 
			cin.getline(per,100,'\n')
 
			out.write("\n",1);
 
			out.write(per,strlen(per));
 
			out<< "\n";
 
			per = "asdfgh";
 
			out.write(per,strlen(per));
 
			out.write((char *)&i,5);
 
			out.write(per,strlen(per));
 
			return 0;
		}
		int read_2()
		{
			char * buffer;
 
			long size;
 
			ifstream in("ss.txt",ios::in|ios::binary|ios::ate);//try without any of these flags.
 
			size = in.tellg();
 
			in.seekg (0, ios::beg);
 
			buffer = new char [size];
 
			in.read (buffer, size);
 
			in.close();
 
			cout << "the complete file is in a buffer...\n";
 
			cout<<buffer;
 
			delete[] buffer;
 
			return 0;
		}
 
 
};
 
void main()
{
	emp e;
	e.write2();//Writes to a file in binary format even if the input data has space. eg:- 
	e.read_2();//Reads a binary file.
}
#include<fstream.h>
#include<iostream.h>
#include<string.h>
using namespace std;
class emp
{
	public:
		char *per;
int i;
	int write2()
		{		
			ofstream out("ss.txt",ios::app | ios::binary );

			cout<<"Enter some character ....\n";

			per = new char[100];

			cin.getline(per,100,'\n')
			
			out.write("\n",1);
			
			out.write(per,strlen(per));
			
			out<< "\n";

			per = "asdfgh";

			out.write(per,strlen(per));

			out.write((char *)&i,5);
			
			out.write(per,strlen(per));
			
			return 0;
		}
		int read_2()
		{
			char * buffer;

			long size;

			ifstream in("ss.txt",ios::in|ios::binary|ios::ate);//try without any of these flags.

			size = in.tellg();

			in.seekg (0, ios::beg);

			buffer = new char [size];

			in.read (buffer, size);

			in.close();

			cout << "the complete file is in a buffer...\n";

			cout<<buffer;

			delete[] buffer;
			
			return 0;
		}


};

void main()
{
	emp e;
	e.write2();//Writes to a file in binary format even if the input data has space. eg:- 
	e.read_2();//Reads a binary file.
}
    C++ Syntax (Toggle Plain Text)  #include<fstream.h>#include<iostream.h>#include<string.h>using namespace std;class emp{	public:		char *per;int i;	int write2()		{					ofstream out("ss.txt",ios::app | ios::binary ); 			cout<<"Enter some character ....\n"; 			per = new char[100]; 			cin.getline(per,100,'\n') 			out.write("\n",1); 			out.write(per,strlen(per)); 			out<< "\n"; 			per = "asdfgh"; 			out.write(per,strlen(per)); 			out.write((char *)&i,5); 			out.write(per,strlen(per)); 			return 0;		}		int read_2()		{			char * buffer; 			long size; 			ifstream in("ss.txt",ios::in|ios::binary|ios::ate);//try without any of these flags. 			size = in.tellg(); 			in.seekg (0, ios::beg); 			buffer = new char [size]; 			in.read (buffer, size); 			in.close(); 			cout << "the complete file is in a buffer...\n"; 			cout<<buffer; 			delete[] buffer; 			return 0;		}  }; void main(){	emp e;	e.write2();//Writes to a file in binary format even if the input data has space. eg:- 	e.read_2();//Reads a binary file.} #include<fstream.h>
#include<iostream.h>
#include<string.h>
using namespace std;
class emp
{
	public:
		char *per;
int i;
	int write2()
		{		
			ofstream out("ss.txt",ios::app | ios::binary );

			cout<<"Enter some character ....\n";

			per = new char[100];

			cin.getline(per,100,'\n')
			
			out.write("\n",1);
			
			out.write(per,strlen(per));
			
			out<< "\n";

			per = "asdfgh";

			out.write(per,strlen(per));

			out.write((char *)&i,5);
			
			out.write(per,strlen(per));
			
			return 0;
		}
		int read_2()
		{
			char * buffer;

			long size;

			ifstream in("ss.txt",ios::in|ios::binary|ios::ate);//try without any of these flags.

			size = in.tellg();

			in.seekg (0, ios::beg);

			buffer = new char [size];

			in.read (buffer, size);

			in.close();

			cout << "the complete file is in a buffer...\n";

			cout<<buffer;

			delete[] buffer;
			
			return 0;
		}


};

void main()
{
	emp e;
	e.write2();//Writes to a file in binary format even if the input data has space. eg:- 
	e.read_2();//Reads a binary file.
} 

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mksakeesh

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Aug 19th, 2008

Re: Need to write an integer to a binary file

Well.. whats your problem ?

William Hemsworth

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Aug 19th, 2008

Re: Need to write an integer to a binary file

I am not able to perform the step "out.write((char *)&i,5);", I am trying to log the count for each time we call the write2() function, but i am not able to enter integer value to a binary file.

mksakeesh

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Aug 19th, 2008

Re: Need to write an integer to a binary file

line 26: that just caused a memory leak. Where did the memory allocated by new operator on line 16 go??? Answer: the Bit Bucket. You have to call delete[] before reusing that pointer on line 26.

>>I am not able to perform the step "out.write((char *)&i,5);",
Suggestion: Create a static counter at the top of the write2() function, increment it, then write it. That way it will not have to depend on something else writing it

C++ Syntax (Toggle Plain Text)
int write2()
{
    static int counter = 0;
    counter++;
    out.write(&counter, sizeof(int));
    // rest of function here
}
int write2()
{
    static int counter = 0;
    counter++;
    out.write(&counter, sizeof(int));
    // rest of function here
}

Ancient Dragon

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Aug 19th, 2008

Re: Need to write an integer to a binary file

try changing the line like this:

C++ Syntax (Toggle Plain Text)
out.write(reinterpret_cast<char*>( &i ) , sizeof i);
out.write(reinterpret_cast<char*>( &i ) , sizeof i);

That should save the integer, but this saves it in the form of binary, so its not readable if you open it in notepad.

William Hemsworth

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Aug 19th, 2008

Re: Need to write an integer to a binary file

Can you please explain what a bit bucket is?

mksakeesh

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Aug 19th, 2008

Re: Need to write an integer to a binary file

Any memory that you allocate should be deleted using the delete keyword otherwise it will case a memory leak. Even though AD has already said it, on line 26 you have assigned the pointer per to point at the characters "asdfgh" and you have ditched the 100 characters that you allocated on line 16. If you want to fill that array with a string, use strcpy.

William Hemsworth

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Aug 19th, 2008

Re: Need to write an integer to a binary file

Suggestion of AD has produced compilation error as:-
Error E2034 binaryfilewriting.cpp 64: Cannot convert 'int *' to 'const char *' i
n function emp::write2()
Error E2342 binaryfilewriting.cpp 64: Type mismatch in parameter 's' (wanted 'co
nst char *', got 'int *') in function emp::write2()
*** 2 errors in Compile ***

line 64 here is "out.write(&i, sizeof(i));"

and trying with "out.write(reinterpret_cast<char*>( &i ) , sizeof i);", has run well, but when file is opened it is showing some unwanted characters. I have opened the file in editplus.

mksakeesh

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Aug 19th, 2008

Re: Need to write an integer to a binary file

>>Error E2034 binaryfilewriting.cpp 64: Cannot convert 'int *' to 'const char *' i

>> out.write(&counter, sizeof(int));
That should have been typecast, like this:
out.write((char*)&counter, sizeof(int));

Ancient Dragon

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Re: Need to write an integer to a binary file

Click to Expand / Collapse Quote originally posted by mksakeesh ...

Can you please explain what a bit bucket is?

Click here

Last edited by Ancient Dragon; Aug 19th, 2008 at 8:51 am.

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