Отправлено: 25.07.13 10:44. Заголовок: Basic c++ for loop help

#include <iostream>
using namespace std;
int main()
{

{
int i=0;
float input;
for (;input!=-1;)
{
cout<<"Enter a Grade or -1 to exit: ";
cin>> input;
if (input!=-1)
i++;
}
{

cout<<"Number of Grades Entered: "<<i<<endl;
cout<<"Grade Average: "<<input/i;
}
}
return 0;
}

What I'm making is a for loop average calculator. There is no limit on how many grades I can put. So basically once I enter a bunch of grades and input -1, I will get the average. The problem is whenever I try to input -1 it replaces the "input"value which ends up with it averaging -1. I searched google and everything I just can't find a accurate answer.

The output should be something like this:

Enter a Grade or -1 to exit: 86.5
Enter a Grade or -1 to exit: 92.6
Enter a Grade or -1 to exit: 84.7
Enter a Grade or -1 to exit: 83.8
Enter a Grade or -1 to exit: -1

Number of Grades Entered: 4
Grade Average: 86.9

 Отправлено: 25.07.13 21:45. Заголовок: first of all why did..

first of all why did you mark your post as for reading only by administrator? I do not see that it is necessary. So would you like to remove this mark from your post?

As for the code then these statements

float input;
for (;input!=-1;)

are already wrong because variable input was not initialized. So it has an arbitrary value that can be equal to for example -1.

The valid code can look the following way


#include <iostream>

using namespace std;

int main()
{
const float sentinel = -1.0f;
int i = 0;
float input;
float sum = 0.0f;

do
{
cout << "Enter a Grade or " << sentinel << " to exit: ";
cin>> input;

if ( input != sentinel )
{
sum += input;
i++;
}
} while ( input != sentinel );

cout << "Number of Grades Entered: " << i << endl;
if ( i != 0 ) cout << "Grade Average: " << sum / i << endl;

return 0;
}