Help needed about data input into a text file

[qingze]

I want to input data into text file while not deleting the original data in the file and I use something as

	ofstream writefile;
	writefile.open("example1.txt");
        if (writefile.is_open())
        {
			for(j=0; j<N; j++)
			{
	        	writefile<<arrayQ[j][M-1];
	        	writefile<<" ";
        	}
            for(j=0; j<N; j++)
	        {
	    		writefile<<arrayP[j][M-1];
	    		writefile<<" ";
   	        }
            writefile.close();
	    }

But this will delete the original data. Anyone know how to solve this?

[writetonsharma]

Open file in append mode ?

[qingze]

What do you mean by append mode? Can you give a sentence?

[writetonsharma]

http://www.cplusplus.com/reference/fstream/ofstream/ofstream/

std::ofstream ofs ("test.txt", std::ofstream::out | std::ofstream::app);