how to input multiple variables through single scanf - c

Question

The question
A maths teacher asks her students to give 3 examples for positive odd numbers. When the student specifies a correct answer, his/her score is incremented by 1. When the student specifies a positive even number, his/her score is decremented by 0.5. When the student specifies a negative number, he/she will not be given any more chances to correct his or her mistake and his/her score will be decremented by 1. So a student's turn comes to an end when he/she has correctly specified 3 positive odd numbers or when the student has specified a negative number.
Few students didn't know the difference between odd numbers and even numbers and they made many mistakes and so it was difficult for the teacher to maintain the scores. The teacher asks for your help.
Can you please help her by writing a program to calculate the score?
Sample Input 1:
1
3
5
Sample Output 1:
3.0
Sample Input 2:
1
2
5
6
7
Sample Output 2:
2.0
Sample Input 3:
2
-4
Sample Output 3:
-1.5
Sample Input 4:
3
3
3
Sample Output 4:
3.0
Problem:
here i am not getting how to input multiple variables through single scanf
here is my code
#include<stdio.h>
int main()
{
int a,i;
float b=0;
for(i=1;i<=3;i++)
{
scanf("%d",&a);
do
{
if(a%2==0)
{
b=b-0.5;
}
if(a<0)
{
b--;
}
else if(a%2!=0)
{
b++;
}
printf("%.1f",b);
}
while(a%2!=0);
break;
}
return 0;
}

Answer 1

Look, the following for loop will just iterate only 3 times:
for(i=1;i<=3;i++)
whereas you input can be more than 3 times (see Sample Input 2)!
There are some syntactical issues besides some logical error in your code.
Instead of float b=0; use float b = 0.0;
Note that, if the input is negative even number then the following code will reduce b by 0.5
if(a%2==0)
{
b=b-0.5;
}
Where the immediate if condition will again reduce b by 1.
if(a<0)
{
b--;
}
that will make your result more reduced by 0.5, which is not correct.
As per your problem definition, the Sample Input is variable so that you have to implement your loop as well. Try something like this:
int input, correctResultCount = 0;
float result = 0.0;
while (true) {
scanf("%d", &input);
if (input < 0) {
result--;
break;
}
if (input % 2 == 0) {
result = result - 0.5;
}
if (input % 2 != 0) {
result++;
correctResultCount++;
}
if (correctResultCount == 3)
break;
}
printf("%.1f", result);
Run Live.

Answer 2

**NOTE**
THIS LINE IS IMPORTANT
"A Student's turn comes to an end when he/she has correctly specified 3 positive odd numbers or when the student has specified a negative number"
i.e HE CAN GIVE ANY NUMBER OF EVEN NUMBERS (2,4,6,8,10...) BUT THIS WILL HALT ONLY WHEN A TOTAL OF 3 ODD NUMBERS ARE GIVEN OR A SINGLE NEGATIVE NUMBER.
#include <iostream>
using namespace std;
int main()
{
int num;
float marks=0.0 ;
for(int i=0;i<3;)
{
cin>>num;
if(num<0)
{
marks=marks-1;
break;
}
else if(num%2==0)
{
marks=marks-0.5;
}
else{
marks=marks+1;
i++;
}
}
cout<<"Final MArks Are :"<<marks<<endl;
}
SAMPLE INPUT & OUTPUT 1:
1 3 5 ->3.0
SAMPLE INPUT & OUTPUT 2:
1 2 5 6 7 -> 2.0