do-while loop "enter more (y/n)" - character issue - c

Question

So I'm working on basic C skills, and I want to design a code which enters as many numbers as the user wants. Then, it should display the count of positive,negative & zero integers entered.
I've searched Google & StackOverflow. The code seems fine according to those programs.
It compiles & runs. But whenever I input anything after the prompt "enter more? y/n", it returns to the code..
Please have a look at the code below:
#include<stdio.h>
int main()
{
int no,count_neg=0,count_pos=0,count_zero=0;
char ch='y';
clrscr();
do
{
puts("Enter number");
scanf("%d",&no);
if (no>0)
count_pos++;
else if (no<0)
count_neg++;
else
count_zero++;
puts("want more? - y/n ");
scanf("%c",&ch);
}
while (ch=='y');
if (ch=='n')
{
printf("No of positives = %d",count_pos);
printf("No of negatives = %d",count_neg);
printf("No of zeros = %d",count_zero);
}
getch();
return 0;
}

Answer 1

The problem is with "scanf("%c", &ch);"
What happens actually is :
Suppose you enter 'y' as a choice and hit 'enter'(return), the return is a character and
its character value is 10(since its a new line character), thus the scanf takes the 'return'
as its input and continues.
Solution :
1. use getchar() before scanf()
// your code
getchar();
scanf();
//your code
getchar() takes the return value as its input, thus you are left with your actual value.
add '\n' to scnaf()
// code
scanf("\n%c", &ch);
//code
when scanf() encounters the '\n' character it skips it (google about scanf, to know how
and why ), thus stores the intended value inside 'ch'.

Answer 2

A "better" form for:
int main()
is:
int main(void)
clrscr is not standard C.
You ought to check the return-value of any function which might indicate "interesting status," such as a failure condition, and from which you can gracefully deal with the situation. In this case, scanf is such a function.
I believe that your first do ... while condition will become false because it will pick up the newline character following your first scanf call. You might want to read about getchar or getc, instead of using scanf for the task of checking whether or not to run the loop again. You can "eat" unwanted characters, including a newline.

Answer 3

Here, I have corrected the problem. The problem was this that the "enter" you press after each number is a character and is takenup by the scanf() as it is there to scan some characters. So I have added a getchar(); before the scanf();so the "enter" is taken up by getchar(); and scanf() is now free to take your input.
#include<stdio.h>
int main()
{
int no,count_neg=0,count_pos=0,count_zero=0;
char ch='y';
clrscr();
do
{
puts("Enter number");
scanf("%d",&no);
if(no>0)
count_pos++;
else if(no<0)
count_neg++;
else
count_zero++;
puts("want more? - y/n ");
getchar();//<---- add this here
scanf("%c",&ch);
}
while(ch=='y');
if(ch=='n')
{
printf("No of positives = %d",count_pos);
printf("No of negatives = %d",count_neg);
printf("No of zeros = %d",count_zero);
}
getch();
return 0;
}

Answer 4

To fix the input is to use a C String like this scanf("%s",...);
This might break if you input more than one character because scanf will keep reading until the user hits enter, and your ch variable is only enough space for one character.

Answer 5

I run your code in Online compiler. I am not sure about other compiler.
I slightly changed your code. i.e., first i read char then int. If i do not change the order, char variable holds int variable value. This is the reason ( ch variable holds values of no variable).
#include<stdio.h>
int main()
{
int no,count_neg=0,count_pos=0,count_zero=0;
char ch='y';
do
{
puts("Enter number");
scanf("%c",&ch);
scanf("%d",&no);
if(no>0)
count_pos++;
else if(no<0)
count_neg++;
else
count_zero++;
puts("want more? - y/n ");
}
while(ch=='y');
if(ch=='n')
{
printf("No of positives = %d",count_pos);
printf("No of negatives = %d",count_neg);
printf("No of zeros = %d",count_zero);
}
return 0;
}
EDIT:
whenever integer and char are read through keyboard. it stores int value and enter key value. so this is the reason.
You have to add
scanf("%d",&no);
you code
......
.....
fflush(stdin);
scanf("%c",&ch);

Answer 6

use:
ch = getche();
instead of:
scanf("%c", &ch);