Thread: Input Tolerance

Hi guys,

Here's a little bit of my code I'd like help with (I can't post it all as it's an assignment, but I've completed this portion for you to test if necessary):

Code:

#include <stdio.h>

int main (void)
{ int n;

do {
         
            printf ("\nHow many resistors would you like to enter?\n  [2 to 10 Resistors can be checked]\n\n");
         
            scanf ("%d", &n);
         
            if (n < 2 || n > 10)
               { printf ("\nYou have entered a number out of range.\nPlease re-enter!\n"); }           
            
            }   while (n < 2 || n > 10);
                
                printf ("\nNumber of resistors to test: %d\n", n);
system ("PAUSE");
return (0);
}

I'd like to implement the following code into this part of my program, such that if the user does not input a digit, or inputs a character, then the program will output an error message "Input not accepted".

I don't want it to display the bit where it says "one converted as..", if chk does equal 1 then I want it to continue the program as normal.

Code:

#include <stdio.h>


int main (void)
{   int x, chk;


    printf ("\n Input one decimal\n");
    chk = scanf ("%d", &x);
    
    if (chk == 1)
       printf ("\n one converted as %d\n",x);
    else
        printf ("\nInput not accepted");
        


system ("PAUSE");
return (0);
}

No matter how I try to implement it, everytime I hit a character it'll just initiate an endless loop.

How can I do it? Or can you not do it inside a do while loop?

Thanks in advance!

on line 10 in your second sample add..

Code:

while (getchar() != '\n');

It goes into an infinite loop because scanf() is not purging the characters out of the input buffer and keeps re-reading the same thing over and over again.

Cheers!

Run into a slight problem here;

Code:

do {
         
            printf ("\nHow many resistors would you like to enter?\n  [2 to 10 Resistors can be checked]\n\n");
            
            gets(vld);
            chk = sscanf (vld, "%d", &n);
            
            if (chk != 1)
               { printf ("\nERROR; You have entered a character.  Please Enter a number!\n"); }
               else
               if (n < 2 || n > 10)
               { printf ("\nYou have entered a number out of range.\nPlease re-enter!\n"); }  
            
            }   while (n < 2 || n > 10);

I've used this method to the other two scanf requests further down my program and work fine, but this one is being silly....everytime I enter a letter it'll come out with the error but also just input 2 into the number of resistors, and not ask the user to re-enter again...

can anyone help?

Thanks!

Ok, just retested...

if I enter 3....it'll keep asking me to re-enter until i've re-entered "3" three times.
it's doing it with any input number .

Originally Posted by nelly26

Cheers!

Run into a slight problem here;

Code:

do {
         
            printf ("\nHow many resistors would you like to enter?\n  [2 to 10 Resistors can be checked]\n\n");
            
            gets(vld);
            chk = sscanf (vld, "%d", &n);
            
            if (chk != 1)
               { printf ("\nERROR; You have entered a character.  Please Enter a number!\n"); }
               else
               if (n < 2 || n > 10)
               { printf ("\nYou have entered a number out of range.\nPlease re-enter!\n"); }  
            
            }   while (n < 2 || n > 10);

I've used this method to the other two scanf requests further down my program and work fine, but this one is being silly....everytime I enter a letter it'll come out with the error but also just input 2 into the number of resistors, and not ask the user to re-enter again...

can anyone help?

Thanks!

Delete line 5 ... and stop using gets altogether. There's all kinds of reasons not to use it and not one good one why you need it.
Add...

Code:

while(getchar() != '\n');

Right after your scanf().

Also lose the for() loops, that's why it's repeating.

Your entry loops should look like this....

Code:

do
   printf("This is to prompt the user : ");
while( (scanf("%d", &variable) < 1) || (variable < minvalue) || (variable > maxvalue));