Thread: First C program

Originally Posted by Stormweaver1

so i deleted the isqrt.h but now its complaining that isqrt.h doesn't exist again.

I'm very confused. I'll keep trying different things though.

isqrt.h contains a prototype ONLY. If you don't know what the word prototype means, look it up or ask. But there should be NO code, just a prototype.

no i don't know what a prototype is . I just saved isqrt.c as isqrt.h

ok i'll google it.

alright I googled it and searched for it on these forums clicked a few links and I still don't understand what you mean by a prototype.

Originally Posted by Stormweaver1

alright I googled it and searched for it on these forums clicked a few links and I still don't understand what you mean by a prototype.

The first link from Google is http://en.wikipedia.org/wiki/Function_prototype which seems amazingly straightforward to me.

A function prototype is needed when you create your own function. For example:

Code:

#include <stdio.h>

void msg(void);    /* This is the prototype */

int main()
{
        /* Displays Hello, World */
        msg();
        return(0);
}

void msg(void)
{
        printf("Hello, World!");
}

Don't feel bad, I'm pretty new to C myself.

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So i changed isqrt.h to a "prototype"

Code:

int isqrt(int n);

and it appears to work! Thank you very much for your help. I have learned more from you then I have from a lecture.

Now onto question #2 :P

Sure. What question do you have?

Alright Question to is as follows.

"Write a function sumsqr that consumes a non-negative integer n and prints all pairs (x, y)
such that x and y are nonnegative integers, x >= y, and x^2 + y^2 = n. Each pair is printed
on a separate line without the parentheses or comma. You may either print them in order of
increasing x or decreasing x. For example, the call sumsqr(50) would print either:
5 5
7 1
or
7 1
5 5
Your program should be able to list all 18 ways to write 446265625 as the sum of two
squares.
To submit: sumsqr.c, sumsqr-driver.c."

Now after looking at the question I realized that the highest possible number will be the square root of the number. So we're going to be implementing question #1.

sumsqr-driver.c looks like

Code:

#include <stdio.h>

#include "sumsqr.h"

int main() {
              printf("%d", sumsqr(50));
              return 0;
}

sumsqr.c is

Code:

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

#include "isqrt.h"

int sumsqr(int n) {
            int a = 0;
            int b = 0;
            int max = isqrt(n);
            if (a == max) {
                        a = 0;
                        b = b+1;
                        return sumsqr(int n);
            } else {
            for (int i=1; i <= max; i=i+1) {
            if (a*a + b*b == n) {
                        printf("%d %d", a, b);
                        a = a+1;
                        return sumsqr(int n);
            } else {
                        a = a+1;
                        return sumsqr(int n);
            }
            }
}

and sumsqr.h contains which was given to us in a different part of the question

Code:

void sumsqr(int n);

And I'm kind of new to the whole prototype thing. But correct me if I'm wrong.
It is saying. It consumes a number and produces a void and in this case void is a set of printfs.

when i try to compile it using the line

Code:

gcc -std=c99 -O -o sumsqr sumsqr-driver.c sumsqr.c -lm

I get the errors

sumsqr-driver.c: In function 'main':
sumsqr-driver.c:6: error: invalid use of void expression
sumsqr.c: In function 'sumsqr':
sumsqr.c:13: error: parse error before "int"
sumsqr.c:19: error: parse error before "int"
sumsqr.c:22: error: parse error before "int"
sumsqr.c:25: error: pares error at end of input

~Stormweaver1~(I'm going for supper but I should be back in 20)