input checking problem..

ggngn

One suggestion is to read a whole lines worth of input into a char array variable and then use the strtod function on that buffer. If the "end" pointer argument to that function points to a null then the information was parsed properly. If it points to something else, i.e. the conversion of the text into an integer stopped short for some reason (such as encountering the first 'g' in "1gghjk"), then you know something other than a simple integer value was entered and can reprompt for more data.

Incidentally, I would not use recursion for the clean and main_menu functions. The reason you are using it in this instance is not something recursion was really meant to solve.

[edit]Oh, and main returns an int. [/edit]

This is a little smoother, imo:

Code:

input1 = 0;

while(input1 == 0)
   {
   printf(" Enter Your Choice: ");
   input1 = scanf("%d", &opt);
   }

The program keeps looping back to query the user and get the input value,
rather than just ask once, and then run on. Very easy to add all kinds of test
for good input, as well.

i solved it

Originally Posted by Adak

This is a little smoother, imo:

Code:

input1 = 0;

while(input1 == 0)
   {
   printf(" Enter Your Choice: ");
   input1 = scanf("%d", &opt);
   }

The program keeps looping back to query the user and get the input value,
rather than just ask once, and then run on. Very easy to add all kinds of test
for good input, as well.

Uh, no...

That still has the problem with "1gghjk", the scanf call will return 1 and it will also return 1 to the opt variable. The rest of the string "gghjk" (garbage) will still be in the input stream/buffer. And god forbid you enter something that doesn't start with a numerical char like "gghjk1", the scanf will return 0 since there was nothing to convert into an int and the stream will still have the "gghjk" in it and you'll loop endlessly.

Originally Posted by hk_mp5kpdw

Uh, no...

That still has the problem with "1gghjk", the scanf call will return 1 and it will also return 1 to the opt variable. The rest of the string "gghjk" (garbage) will still be in the input stream/buffer. And god forbid you enter something that doesn't start with a numerical char like "gghjk1", the scanf will return 0 since there was nothing to convert into an int and the stream will still have the "gghjk" in it and you'll loop endlessly.

Surprised there isn't a flush in there. Adak's solution looks almost exactly like what I came up with on my own in my programs, except I added a flush after the scanf line.

Code:

#define FLUSH while (getchar() != '\n')

Code:

input1 = 0;

while(input1 == 0)
   {
   printf(" Enter Your Choice: ");
   input1 = scanf("%d", &opt);
   FLUSH;
   }

If this is his only input line in the program, he may not need to do the define, just put the while loop in there directly.

All of this presupposes that he can even use loops, though. His teacher, for whatever reason that god only knows, seems hell bent on banning loops from the class. He's posted like 10 different things, all of them "how do you do this without a loop?" In which case, he'll have to figure out some other way of doing this.

what will happen with your code if scanf or getchar returns EOF?

Do not edit out your posts once you get your answer! How is anyone else having the same trouble supposed to know how you solved it?