Garbage values when writing and reading to a text file

Question

Can Some one help me the problem with this code? I am getting bunch of garbage value !

fstream fs("hello.txt"); if(fs.is_open()) { string s = "hello"; string line; fs << s; while(getline(fs,line)) { cout << line; } cin.get(); } fs.close();

Thank you very much but when I try to do this I am getting same garbage. I am trying to rewrite the first hello with world and trying to print that line

fstream fs("hello.txt"); if(fs.is_open()) { string s = "hello"; string line; fs << s << endl; fs.seekg(0); fs << "world" << endl; fs.seekg(0); while(getline(fs,line)) { cout<<line; } cin.get(); } fs.close();

kennytm · Accepted Answer · 2010-07-06 07:35:07Z

The cursor of fs is at the end of file after you fs << s (this is required to append data to the file properly).

Try to call fs.seekg(0); to move the cursor back to the beginning.

Also, you may need to supply the fstream::trunc or fstream::app flag when constructing fs.

fstream fs("hello.txt", fstream::in | fstream::out | fstream::trunc);

Thank you very much but I edited the code as shown in the post. Now I am getting same garbage value.
@brett: Not reproducible. I got world on the screen. (Call seekg(0) only after you have written everything.)

jon hanson · Accepted Answer · 2010-07-06 07:32:37Z

If hello.txt is empty prior to running the program then it seems to work for me. If the file contains more than 6 or 7 characters then your hello world code will overwrite the first 6/7 chars with "world" followed by the line terminator (which might be 1 or 2 chars depending on the platform). The reminder of the file won't be overwritten and will be subsequently printed by your getline loop.

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