pr07002.cpp

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////////////////////////////////////////
// File Name: pr07002.cpp
////////////////////////////////////////
#include <iostream>
#include <cmath>
#include <cerrno>

////////////////////////////////////////
// The main() function.
////////////////////////////////////////

int main()
{
    double f;

    do
    {
        errno = 0;
        std::cout << "Enter positive float (0 to quit) ";
        std::cin >> f;
        if (f != 0)
        {
            double sq = std::sqrt(f);
            if (errno == 0)
                std::cout << "Square root of " << f
                     << " is " << sq << std::endl;
            else
                std::cout << "Invalid entry" << std::endl;
        }
    }
    while (f != 0);

    return 0;
}