Need to understand how to add values in a loop - c++

Question

#include <iostream>
using namespace std;
int main()
{
int numint, sum, a, b, ctr;
cout << "Enter the number of intervals: ";
cin >> numint;
ctr = 0;
while (ctr != numint)
{
cout << "Enter the lower and upper bounds of the interval: ";
cin >> a;
cin >> b;
ctr++;
}
cout << "The sum of the " << numint << " intervals is: [" << a << "," << b << "]";
return 0;
}
I need to add the upper bounds of the interval (a) and lower bounds of the interval (b). This depends on the amt of intervals there are.

Answer 1

here:
cout << "The sum of the " << numint << " intervals is: [" << a << "," << b << ]";
you are not adding the values but instead just printing them
instead use some accumulator variable and do the math before printing it, like:
int main()
{
int numint,sum,a,b,ctr;
int result = 0;
cout << "Enter the number of intervals: ";
cin >> numint;
ctr=0;
while (ctr!=numint)
{
cout << "Enter the lower and upper bounds of the interval: ";
cin >> a;
cin >> b;
ctr++;
}
result = a + b ;
cout << "The sum of the " << numint << " is: " << result;
return 0;
}

Answer 2

As for what I understood from the question, you first need a int resultA=0 and another for b, and keep adding in the loop:
#include <iostream>
using namespace std;
int main()
{
int numint,sum,a,b,ctr;
int result = 0;
int resultA=0;
int resultB=0;
cout << "Enter the number of intervals: ";
cin >> numint;
ctr=0;
while (ctr!=numint)
{
cout << "Enter the lower and upper bounds of the interval: ";
cin >> a;
cin >> b;
resultA+=a;
resultB+=b;
ctr++;
}
result = resultA + resultB ;
cout << "The sum of the " << numint << " is: " << result;
return 0;
}

Answer 3

I think this is what you are looking for:
#include <iostream>
using namespace std;
int main() {
int numberOfIntervals;
int lowerBound;
int upperBound;
int counter;
int lowerBoundSum = 0;
int upperBoundSum = 0;
cout << "Enter the number of intervals: ";
cin >> numberOfIntervals;
counter = 0;
while (counter != numberOfIntervals) {
cout << "Enter the lower and upper bounds of interval "
<< counter << ": ";
cin >> lowerBound;
cin >> upperBound;
lowerBoundSum += lowerBound;
upperBoundSum += upperBound;
counter++;
}
cout << "The sum of the lower bounds is " << lowerBoundSum
<< endl;
cout << "The sum of the upper bounds is " << upperBoundSum
<< endl;
return 0;
}