Thread: Re-reading chars from stdin

Originally Posted by Dave_Sinkula

Why not use fgets to grab a whole line, and then parse the line using sscanf or such?

Thanks for the suggestion, but the program is for a set exercise, where I'm editing someone else's program (it originally required the user to enter 'n' between each number), and it has specifically told me how I have to go about coding the solution.

Is there no easy way to do what I'm trying to do? The exercise specification says "you can get the next character from input using getchar() and put it back on the input again using putchar()". I've used getchar(), but from all the documentation I've read it looks like putchar() can only be used to print to stdout - not exactly what I want! Has my lecturer got it wrong, or am I missing something?

Thanks,

James

You could try using a function where the output location is accepted as an argument, but instead of using stdout, use stdin. Whether that would put the output into the input buffer, I don't know, but if it does, this might be a route to solving your problem. Those characters would be put onto the end of the buffer queue, though.

Personally, I would create an array and set the program to read one character at a time and store it in the array. Then make a separate function for reading those values and converting it into an int or float. This is kinda the same thing Dave said, though, so I don't know if it would go against your directions.

Originally Posted by Dave_Sinkula

Perhaps ungetc rather than putchar?

Spot on! Thought I'd tried it, but guess not. Passing stdin as the stream (as I see Jaken Veina suggested after I'd tried it, thanks ) seemed to do the trick.

Program now seems to be stuck in an inifinite loop, but it's returning the right answer, which is the main thing!

Thanks so much to everyone who helped me out - added rep for all.