ProgrammingThis forum is for all programming questions.
The question does not have to be directly related to Linux and any language is fair game.
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
I believe GCC for C programs has ungetc which puts a character back in stdin and probably moves the pointer back 1. I need FUNGETC which would put a character back in in FILE * fp and move the pointer back 1. GCC does not seem to have this one. Anyone know how I would go about creating a function to do this? I might be able to get away with using fgetc in a program to preliminary get the string from fp and just move the pointer back for the big string when I form smaller strings. The reason I want this is to move the pointer back if I encounter valid data after getting a CR or LF (\r or \n) before the next valid read after I process the data I now have. Thank you. Alvin...
I was once writing a little recursive-descent compiler that needed this sort of thing, and it always needed to go back only-one character. So, I simply wrote that functionality into my homebrew getchar/ungetchar routines: "ungetchar" simply set a global boolean flag which caused "getchar" to un-set the flag and return the same character as before, instead of reading a new character from the source. Problem solved.
(As a bug-check, if "ungetchar" found the flag to be already-raised, it threw an exception.)
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.