Nsryjdtyk

In this code it need to calculate the number of times the operators appear.
It doesn't calculate it and while running the code it prints "Please enter a note. to finish press Q:" twice and i don't know whats wrong.

#include <stdio.h>



int main(void)

{



    char note;

    int result1 = 0, result2 = 0, result3 = 0, result4 = 0;





    do

    {

        printf("Please enter a note. to finish press Q:n");

        scanf("%c", &note);

        switch (note)

        {

        case'+':

            result1 = result1 + 1;

            break;

        case'-':

            result2 = result2 + 1;

            break;

        case'*':

            result3 = result3 + 1;

            break;

        case'/':

            result4 = result4 + 1;

            break;

        }



    } while (note != 'Q');



    printf("+ appears %d timesn", result1);

    printf("- appears %d timesn", result2);

    printf("* appears %d timesn", result3);

    printf("/ appears %d timesn", result4);



    system("pause");

}

To debug this, insert

  printf("note='%c'n", note);

immediately after the scanf.
You'll see the problem immediately.

Using scanf("%c", %c), you will be reading one character at a time. Which is fine, but..

scanf will not "re-scan" for input, until the buffer is clear.

So, if the user were to input something longer than 1 character, your loop will iterate for every character the string is long + 1 (n counts as a character).

Example (note it loops 3 times +, +, n):

Please enter a note. to finish press Q:

++

Please enter a note. to finish press Q:

Please enter a note. to finish press Q:

Please enter a note. to finish press Q:

That's the trick. You need to change your code to accommodate this (i.e. hide the please enter message until empty or read a char array note[128]... scanf('%s', note) vs. single character with a sub loop to iterate the over the input, etc. or some other way).