sqrt

[yawningdog]

I'm trying to get this function to work, but I must be missing something. Little help?

#include <stdio.h>
#include <math.h>

char line[100];
int square;
int root;

int main()
{
printf("Enter a number: ");
fgets(line, sizeof(line), stdin);
sscanf(line, "%d", &square);

root = sqrt(square);
printf("The square root of %d is %d.", square, root);
return(0);
}

[saturn-vk]

and the error message is?

[evac-q8r]

Hey yawningdog,

I think that your problem is the variable named root. First of all sqrt takes a double precision number and returns another double precision, i.e. a float. You have root defined as an integer. Secondly, it may be the name of the variable root. I remember once in my programming experiences that I named a window variable root because it was going to be the root window with a bunch of children windows associated with it and I simply changed the name of the variable to something different and then everything mysteriously became OK.

EVAC

[Citadel]

Originally posted by yawningdog
I'm trying to get this function to work, but I must be missing something. Little help?

#include <stdio.h>
#include <math.h>

char line[100];
int square;
int root;

int main()
{
printf("Enter a number: ");
fgets(line, sizeof(line), stdin);
sscanf(line, "%d", &square);

root = sqrt(square);
printf("The square root of %d is %d.", square, root);
return(0);
}


Among other suggestions use the lm option:
gcc -lm program.c

[yawningdog]

Cool, thanks. Changed the ints to floats and the ds to fs and all is go.

By the way, what's the -lm flag for?

[bwkaz]

It requests that gcc link in its math library. The math library isn't linked by default, because it contains a whole bunch of functions that normally aren't used.

/lib/libm.so is the file, in case you're interested. Not that it's readable, though, except through nm or something. *shrug*

[GlennaclawZ]

it is math.sqrt(int) try that there is also another command that is math.pow(num, power) as well to reverse it for future reference.

[bwkaz]

In Java, perhaps (actually it's Math.sqrt(...) and Math.pow(x, y)).

But these functions don't even exist in C -- if you try to compile a program that says "math.sqrt" or "Math.sqrt" anywhere in it, you'll get errors about "undefined symbol math" or "undefined symbol Math", I think. I know it won't work.

;)