Thread: C++problem to solve

ok im trying to write a c++ program that will determine the square root of 138 without using a calculator or the math library. any suggestions

Here, I found this searching my old codes... I wrote it when I was still learning C and C++... Yes, I keep my old codes and the codes I find interesting today, just to compare to the code of tomorrow.

I remember that I wrote it using a square root algorithm I found on the web... But I dont remember very well how it works... Anyway, here it is.. Hope it helps in some way:

Code:

#include <stdio.h>

int getroot(int value)
{
        int count = 0;
        for(count = 0; (count * count) != value &&
                (count * count) <= value; count++)
                continue;
        if((count * count) == value)
                return(count);
        else
                return(0);
}
double fullroot(double value)
{
        double count;
        double reval;
        for(count = 0; (count * count) != value &&
                (count * count) <= value; count++)
                continue;
        if((count * count) == value)
                return(count);
        else
        {
                reval = (count - 1) + 0.1;
                for(; (reval * reval) < value && reval != (reval + 0.999998);
                        reval = reval + 0.000001)
                        continue;
                return((reval - 0.000001));
        }
}


int main(int argc, char **argv)
{
    printf("Square root of 16:%d\n", getroot(16));
    printf("Square root of 10:%f", fullroot(10));
    getchar();
    return(0);
}

Thanks for the help @ dante and i understand what you're saying @ g4j31a5, all i wanted was a little direction not a full layout but i know @ dante was just trying to help

Originally Posted by iMalc

"Quake's fast inverse square root" to be more precise

O_o

Code:

sqrtn = n * invsqrt(n);

If you really don't mind the loss of precision.

Soma