C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Read and write the same file          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message YUS Guest Posted: Mon Jan 30, 2006 5:01 pm    Post subject: Read and write the same file First of all, I'm a c++ beginner.. as u will see.. I'd like to do this: - The code open a file - it searchs for the string "BUDGET = " - the budget value is overwritten or at least the entire row. CODE: fstream file; memset(buf,0,512); file.open(nomefile, ios::out | ios::in); do{ file.getline(buf, 512, '\n'); } while(!strncmp(buf, "BUDGET", 6)); file << "BUDGET = " << budget << endl; The problem is that the file is not written, no changes are made to the file. I've also tried with ios::app but with no results. How I can do ? Thanks to all. -- oooO Oooo ( ) YUS ( ) \ ( Para todos, todo, ) / \_ ) nada para nosotros. ( _/ Back to top TB Guest Posted: Mon Jan 30, 2006 5:01 pm    Post subject: Re: Read and write the same file YUS sade: Quote: First of all, I'm a c++ beginner.. as u will see.. I'd like to do this: - The code open a file - it searchs for the string "BUDGET = " - the budget value is overwritten or at least the entire row. CODE: fstream file; memset(buf,0,512); file.open(nomefile, ios::out | ios::in); do{ file.getline(buf, 512, '\n'); } while(!strncmp(buf, "BUDGET", 6)); file << "BUDGET = " << budget << endl; The problem is that the file is not written, no changes are made to the file. I've also tried with ios::app but with no results. How I can do ? Thanks to all. I believe, IIRC, that you after a read must do a seekp() before you write, and vise versa (but with seekg()). -- TB @ SWEDEN Back to top Jon Rea Guest Posted: Mon Jan 30, 2006 5:01 pm    Post subject: Re: Read and write the same file YUS wrote: Quote: First of all, I'm a c++ beginner.. as u will see.. I'd like to do this: - The code open a file - it searchs for the string "BUDGET = " - the budget value is overwritten or at least the entire row. CODE: fstream file; memset(buf,0,512); file.open(nomefile, ios::out | ios::in); do{ file.getline(buf, 512, '\n'); } while(!strncmp(buf, "BUDGET", 6)); file << "BUDGET = " << budget << endl; The problem is that the file is not written, no changes are made to the file. I've also tried with ios::app but with no results. How I can do ? Thanks to all. You need to close the filestream to write the current memory to the file... Jon Rea Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.