C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  cin.getline problems in case          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Simon Gibson Guest Posted: Thu Feb 26, 2004 12:30 pm    Post subject: cin.getline problems in case Hi there, im trying to write a program where you can write reports and save them into an array. im having problems with getting the string into an array tho it seems to be skipping over the cin.getline function entiryly and going back upto the start of the menu. the problem seems to lie with 'n' bit if i change that to say 'a' it will run fine but accept a as ending the input. any help getting the 'n' working is appreciated!! heres the code: //--------------------------------------------- //program to store match reports into an array and view them // // //--------------------------------------------- #include <iostream> using namespace std; int main() { const int MAX = 600; char matches[10][MAX]; //array declaration int choice = 0; //number choice int count = 0; //array location count int i = 0; //I initialised here cos cant in case?? while (choice != 3) { cout << "Welcome to the match database"; //menu. cout << endl << "1. View Entrys" << endl << "2. Add Entry" << endl << "3. End program" << endl << "please choose an option: "; cin >> choice; switch(choice) //choice selection { case 1: //view entrys for(i = 0;i < count; i++) //reset i to view full list each time { cout << endl << "Match report number: " << i << endl << *(matches+i); //view matches. } break; case 2: // add entry cout << endl // Prompt for input << "Enter Your Report. it must be less than " << MAX << " characters:" << endl; cin.getline ( matches[count], MAX, 'n'); // add to array count++; //inc count break; case 3: //quit program return 0; break; default: cout << endl << "not a valid number " << endl; } } return 0; } Back to top John Harrison Guest Posted: Thu Feb 26, 2004 12:52 pm    Post subject: Re: cin.getline problems in case "Simon Gibson" <simon.gibson (AT) blueyonder (DOT) co.uk> wrote Quote: Hi there, im trying to write a program where you can write reports and save them into an array. im having problems with getting the string into an array tho it seems to be skipping over the cin.getline function entiryly and going back upto the start of the menu. the problem seems to lie with 'n' bit if i change that to say 'a' it will run fine but accept a as ending the input. any help getting the 'n' working is appreciated!! heres the code: The problem is that you don't fully understand how the combination of cin >> i; and cin.getline() works, (hint cin >> i never reads a newline and cin.getline() reads upto the next newline, so what do you think will happen when you combine the two?). This question is covered in the FAQ http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.6 john Back to top John Harrison Guest Posted: Thu Feb 26, 2004 1:04 pm    Post subject: Re: cin.getline problems in case Quote: This question is covered in the FAQ http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.6 john I think the FAQ is less than helpful on this question, here's exactly what happens. Your program asks for a menu option and the user types 2 <newline> Then your program asks for a report and the user types this is my report <newline> At this point cin.getline() starts reading characters. Now at this point how many newlines have been read so far? You think the answer is one and so you can't understand why getline seems to skip the report. But the answer is zero, because cin >> i NEVER reads newlines (assuming i is a number). The newline that was typed after the menu option is still waiting to be read and getline reads it and stops. This is why, after interactive line based input its a good idea to add cin.ignore(INT_MAX); after the input of a number, to clear out any unread newlines. Use the header file <limits.h> to get the INT_MAX constant. john Back to top Simon Gibson Guest Posted: Thu Feb 26, 2004 2:40 pm    Post subject: Re: cin.getline problems in case Cheers for that, one thing tho, i tried using the cin.ignore(INT_MAX); but when i entered the number 2 to go into the enter match bit it didnt come up it just kept letting me press enter with nothing happening. i tried using cin.ignore() and it works fine, could you explain the INT_MAX bit? im only just learning so any info is appreciated. cheers si "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote Quote: This question is covered in the FAQ http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.6 john I think the FAQ is less than helpful on this question, here's exactly what happens. Your program asks for a menu option and the user types 2 <newline Then your program asks for a report and the user types this is my report At this point cin.getline() starts reading characters. Now at this point how many newlines have been read so far? You think the answer is one and so you can't understand why getline seems to skip the report. But the answer is zero, because cin >> i NEVER reads newlines (assuming i is a number). The newline that was typed after the menu option is still waiting to be read and getline reads it and stops. This is why, after interactive line based input its a good idea to add cin.ignore(INT_MAX); after the input of a number, to clear out any unread newlines. Use the header file <limits.h> to get the INT_MAX constant. john Back to top Thomas Matthews Guest Posted: Thu Feb 26, 2004 3:25 pm    Post subject: Re: cin.getline problems in case Simon Gibson wrote: Quote: "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote in message news:c1kqn8$1jkhbu$1 (AT) ID-196037 (DOT) news.uni-berlin.de... This question is covered in the FAQ http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.6 john I think the FAQ is less than helpful on this question, here's exactly what happens. Your program asks for a menu option and the user types 2 <newline Then your program asks for a report and the user types this is my report At this point cin.getline() starts reading characters. Now at this point how many newlines have been read so far? You think the answer is one and so you can't understand why getline seems to skip the report. But the answer is zero, because cin >> i NEVER reads newlines (assuming i is a number). The newline that was typed after the menu option is still waiting to be read and getline reads it and stops. This is why, after interactive line based input its a good idea to add cin.ignore(INT_MAX); after the input of a number, to clear out any unread newlines. Use the header file <limits.h> to get the INT_MAX constant. john Cheers for that, one thing tho, i tried using the cin.ignore(INT_MAX); but when i entered the number 2 to go into the enter match bit it didnt come up it just kept letting me press enter with nothing happening. i tried using cin.ignore() and it works fine, could you explain the INT_MAX bit? im only just learning so any info is appreciated. cheers si 1. Don't top-post. Replies go at the bottom or are interspersed. 2. I believe the ignore syntax should be: cin.ignore(INT_MAX, 'n'); This says to ignore either INT_MAX characters or 'n', which ever occurs first. -- Thomas Matthews C++ newsgroup welcome message: http://www.slack.net/~shiva/welcome.txt C++ Faq: http://www.parashift.com/c++-faq-lite C Faq: http://www.eskimo.com/~scs/c-faq/top.html alt.comp.lang.learn.c-c++ faq: http://www.raos.demon.uk/acllc-c++/faq.html Other sites: http://www.josuttis.com -- C++ STL Library book Back to top John Harrison Guest Posted: Thu Feb 26, 2004 3:43 pm    Post subject: Re: cin.getline problems in case Quote: 1. Don't top-post. Replies go at the bottom or are interspersed. 2. I believe the ignore syntax should be: cin.ignore(INT_MAX, 'n'); This says to ignore either INT_MAX characters or 'n', which ever occurs first. Yes that's right, apologies for my mistake. Without 'n' it means ignore all input, with 'n' it means ignore all input up to the next newline, which is what you want. You can do this (say) cin.ignore(10, 'n'); which means ignore up to 10 characters or until the next newline whichever comes first. INT_MAX is just a way of saying ignore *all* input up to the next newline, which is normally what you want. john Back to top Simon Gibson Guest Posted: Thu Feb 26, 2004 3:57 pm    Post subject: Re: cin.getline problems in case "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote Quote: 1. Don't top-post. Replies go at the bottom or are interspersed. 2. I believe the ignore syntax should be: cin.ignore(INT_MAX, 'n'); This says to ignore either INT_MAX characters or 'n', which ever occurs first. Yes that's right, apologies for my mistake. Without 'n' it means ignore all input, with 'n' it means ignore all input up to the next newline, which is what you want. You can do this (say) cin.ignore(10, 'n'); which means ignore up to 10 characters or until the next newline whichever comes first. INT_MAX is just a way of saying ignore *all* input up to the next newline, which is normally what you want. john sorry about top posting didnt know it was a rule : thanks for the help guys its all clear now si 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.