How to implement a^b without `pow`? - c

Question

I need to write a function to compute a^b but I am not allowed to use pow. Any ideas? I am lost.
It looks like problem is in main now...
Somewhere it gets that vys is what i characterise it. So if i set that vys=1 in main i get 1 in output..
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <unistd.h>
void multiplied(int b, int n)
{
int i=1, vys=1;
while (i<=n)
{
vys *=b;
i++;
}
return vys;
}
main(void)
{
int b=0, n=0, vys=1;
printf("Give numbers b and n but they must be in interval <0,10>!\n");
scanf("%d %d", &b, &n);
if ((b < 0 || b>10) || (n<0 || n>10))
{
printf("Numbers are not in interval <0,10>!\n");
}
else
{
printf("Number is in interval so i continue...\n");
sleep(2);
vys= multiplied(&b, &n);
printf("%d", vys);
}

Answer 1

Let's be explicit.
First, this
void multiplied(int *b, int *n)
returns an int, so say so.
int multiplied(int *b, int *n)
Next, you initialised variables in main: do the same here.
int i, vys;
Like this:
int i=1, vys=1;
Now let's look at the loop:
while (i<=n)
{
vys=*b**b;
i++;
}
As it stands, you are setting vys to something over and over again in the loop.
You want to multiply up, e.g. 2, then 2*2, then 2*2*2, .... if you want a power of two:
while (i<=n)
{
vys *= *b;
i++;
}
Now, you don't need to pass pointers.
int multiplied(int b, int n)
{
int i=1, vys=1;
while (i<=n)
{
vys *= b;
i++;
}
return vys;
}
Edit:
Watch out for when you call the function:
main(void)
{
int b=0, n=0, vys;
//input and checking code as you have it
multiplied(&b, &n); //<---- return ignored
printf("%d", vys); //<-- print uninitialsed local variable
}
Change you last two lines:
vys = multiplied(&b, &n); //<---- return captured
printf("%d", vys); //<-- print returned variable
Edit 2:
With the change to use int in the function and not pointers, pass the ints not their addresses:
vys = multiplied(b, n); //<---- pass the ints not their addresses
printf("%d", vys); //<-- print returned variable, which should vary now

Answer 2

Here you have a simple code:
#include <stdio.h>
long long intpow(int a, int b)
{
long long tempres = 1;
while(b--)
tempres *= a;
return tempres;
}
int main(void) {
printf("%lld\n", intpow(5,10));
return 0;
}
you need much larger int to accommodate the result.
You can play with it yourself: https://ideone.com/4JT6NQ