weired problem in while loop

hello everyone!

i am new here and i have a question.
i wrote a program in c that get a char and 2 numbers and with the char the user entered the program does some actions.
Q is for quitting the program
its all working nice to here, the problem is after i entered the while loop once and entered some inputs i get the result, but then when it comes back to the while loop its shows me the printf give me an error and shows the printf again and after that its ready to get an input.
i tried to debug and for some reason the Variable "c" get a value of "/n" when it comes to the while loop in the second time, and i dont understand why.


i uploaded a picture that shows the problem and added the code.
someone sees the problem?

Thanks.

Code:

---

#include <stdio.h>
#include <conio.h>
#include <math.h>

int main()
{
        int num1,num2;
        int sum,check,min,max,p;
        int gcd,i;
        char c;
        clrscr();
  while(c!='Q')
        {
        num2=0;
        num1=0;
        printf("\nEnter action (Q to quit), and two numbers by that order:");
        scanf("%c", &c);
        switch(c)
        {
                case 'a':
                        scanf("%d%d",&num1, &num2);
                        sum=(num1+num2);
                        check=sum%2;
                        if (check!=0)
                                printf("\nThe average is not a whole number");
                        else
                                printf("\nThe average is a whole number");
                        printf("\n\nThe average is: %.2f", ((float)(num1+num2)/2));
                break;
                case '*':
                        scanf("%d%d",&num1, &num2);
                        printf("\nThe product is: %d", num1*num2);
                break;
                case 'm':
                        scanf("%d%d",&num1, &num2);
                        min=(num1<num2)? num1:num2;
                        printf("The smaller number is: %d", min);
                break;
                case 'M':
                        scanf("%d%d",&num1, &num2);
                        max=(num1>num2)? num1:num2;
                        printf("The larger number is: %d", max);
                break;
                case 'g':
                {
                        scanf("%d%d", &num1, &num2);
                        if(num1<num2)
                       
                        for(i=1;i<=num1;i++)
                        {
                                if(num1%i==0&&num2%i==0)
                                        gcd=i;
                        }
                        else
                        {
                                for(i=1;i<=num2;i++)
                                {
                                        if(num1%i==0&&num2%i==0)
                                                gcd=i;
                                }
                        }       
                       
                                printf("\GCD: %d", gcd);
                       
                break;
                case 'Q':
                  printf("\nProgram Terminated.");
                break;
                case '^':
                  scanf("%d%d", &num1, &num2);
                  p=pow(num1,num2);
                  printf("\nThe result of %d^%d is: %d", num1, num2 , p);
                break;
                }
                default: printf("\nERROR");
                break;
        }
}
  getch();
  return 0;
}

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That is, when you enter your numbers with scanf, it leaves behind a newline (from pressing enter), which is acceptable input for "%c", so you get a "newline" as input.

--
Mats

what can i do to prevent that?

You could add getchar() to each of your switch cases, just above the statement break;

Simple solution would be a getchar() at the end of the loop somewhere.

--
Mats

I find getch() more suitable, I think getchar() accepts only enter.

Quote:

---

Originally Posted by hauzer

I find getch() more suitable, I think getchar() accepts only enter.

---

No, getchar() accepts all characters. getch() is also non-standard, so it won't work on all platforms.

--
Mats

Are you expecting say
a22 33q
to do something meaningful (for example)?

yes, a will say what to do with the 2 numbers you entered, but Q will quit the program.

i tried getch() after the loop, it works fine, but when i press Q to quit the program it doesnt quit it just writes me "program terminated" and i enter to an endless loop

Are you getchar()ing into variable c, so that c no longer has 'Q'?

yes, i put getchar() in c, but Q get me into an endless loop

That's impossible, unless you've modified the code from you're previous post. Please post your current code.

this is the current code, i put the getchar() in the end of the loop

Code:

---

#include <stdio.h>
#include <conio.h>
#include <math.h>

int main()
{
        int num1,num2;
        int sum,check,min,max,p;
        int gcd,i;
        char c;
        clrscr();
  while(c!='Q')
        {
        num2=0;
        num1=0;
        printf("\nEnter action (Q to quit), and two numbers by that order:");
        c=getchar();
        switch(c)
        {
                case 'a':
                        scanf("&#37;d%d",&num1, &num2);
                        sum=(num1+num2);
                        check=sum%2;
                        if (check!=0)
                                printf("\nThe average is not a whole number");
                        else
                                printf("\nThe average is a whole number");
                        printf("\n\nThe average is: %.2f", ((float)(num1+num2)/2));
                break;
                case '*':
                        scanf("%d%d",&num1, &num2);
                        printf("\nThe product is: %d", num1*num2);
                break;
                case 'm':
                        scanf("%d%d",&num1, &num2);
                        min=(num1<num2)? num1:num2;
                        printf("The smaller number is: %d", min);
                break;
                case 'M':
                        scanf("%d%d",&num1, &num2);
                        max=(num1>num2)? num1:num2;
                        printf("The larger number is: %d", max);
                break;
                case 'g':
                {
                        scanf("%d%d", &num1, &num2);
                        if(num1<num2)
                       
                        for(i=1;i<=num1;i++)
                        {
                                if(num1%i==0&&num2%i==0)
                                        gcd=i;
                        }
                        else
                        {
                                for(i=1;i<=num2;i++)
                                {
                                        if(num1%i==0&&num2%i==0)
                                                gcd=i;
                                }
                        }       
                       
                                printf("\GCD: %d", gcd);
                       
                break;
                case 'Q':
                  printf("\nProgram Terminated.");
                break;
                case '^':
                  scanf("%d%d", &num1, &num2);
                  p=pow(num1,num2);
                  printf("\nThe result of %d^%d is: %d", num1, num2 , p);
                break;
                }
                default: printf("\nERROR");
                break;
               
        }
        c=getchar();
}
  return 0;
}

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Like I said. Since you are getchar()ing the '\n' into c, it will never contain the 'Q' it used to have. getchar() into a throw-away variable.

Quote:

---

Originally Posted by Dino

Like I said. Since you are getchar()ing the '\n' into c, it will never contain the 'Q' it used to have. getchar() into a throw-away variable.

---

Or no variable at all.

--
Mats