#include <iostream>
using namespace std;

// Returns true if x is in range [low..high], else false
bool inRange(int low, int high, int x)
{
    return ((x-high)*(x-low) <= 0);
}

int main()
{
    inRange(10, 100, 25)? cout << "Yes\n":  cout  <<"No\n";
    inRange(10, 100, 6)?  cout << "Yes\n":  cout  <<"No\n";
}

Output:

Yes

No

Explanation:

The concept used in above program is subtracting low from x and subtracting high from x and multiplying them. If x is in the range[low,high] then x is greater then or equal to low therefore result of the expression (x-low) is greater then equal to 0, in case of high for x to be in range[low,high], x must be less then or equal to high thus result of the expression (x-high) returns a negative number or 0 thus multiplying these two expression if multiplied result is less then or equal to 0 then a true is returned else false.