Thread: Some basic things

Thanks a lot for writing down the full code. However I had my friend try it and it gives errors. Could it be that it contains C++?

well this is the other way of doing it, may be if its interesting to you

Code:

    if( power < 0 )
        printf("Result &#37;f", ( 1.0 / pow(base, ( power * -1 )))); 
    else
        printf("Resilt %f", pow(base, power));

ssharish

Originally Posted by Nathalie

Thanks a lot for writing down the full code. However I had my friend try it and it gives errors. Could it be that it contains C++?

Yes, cin and cout are C++, the rest is C-compatible, I believe.

Originally Posted by ssharish2005

well this is the other way of doing it, may be if its interesting to you

Code:

    if( power < 0 )
        printf("Result %f", ( 1.0 / pow(base, ( power * -1 )))); 
    else
        printf("Resilt %f", pow(base, power));

ssharish

pow wasn't to be used or we wouldn't be dicussing this.

another thing you may want to consider is the case that num=0 (because you cannot do 0^(-3))

0 * X = 0.
0 / X = 0.
So there's no worry I think.

Originally Posted by Elysia

0 * X = 0.
0 / X = 0.
So there's no worry I think.

reading your code above, with num=0 and pow<0 say pow= -3 you get:

Code:

else if (pow < 0)  // -3<0 
	{
		onum = num;      //  onum = 0
		for (; pow < 1; pow++)
		{
			num /= onum;  // num = 0  / 0  <---- this is the problem
		}
	}

Thanks to all of you for your efforts! Eventually we got it to work with this code, which doesn't contain any C++. (The words are in Turkish now though, don't ask. I believe us is power). Thanks again!

Code:

#include <stdio.h>

                int main()
                {
                int us=0;
                int taban=0;
                float sonuc=1;
                int sayac=1;


                printf("Ussu alinacak sayiyi girin....:D");
                scanf("%d",&taban);
                printf("\nUssu giriniz......:D");
                scanf("%d",&us);

                if (us>0)
                        {
                        for(sayac=1;sayac<=us;sayac++)
                                {
                                sonuc *= taban;
                                }
                        }


                else
                        {
                        for(sayac=1;sayac<=-us;sayac++)
                                {
                                sonuc *= (1 / (float)taban);
                                }
                        }
                printf("%d uzeri %d = %.2f dir",taban,us,sonuc);



                return 0;
                }

Originally Posted by Nathalie

Thanks to all of you for your efforts! Eventually we got it to work with this code, which doesn't contain any C++. (The words are in Turkish now though, don't ask. I believe us is power). Thanks again!

Look at my code above. Don't forget to check for power == 0 (anything raised to 0 is 1) and number == 0 (division by 0 is illegal). Also, you have a bug, I realize.

Here's a condition:
number = 10
power = 3
Result should be 1000, right?
Let's check them loops:

First loop: number = number (10) * number (10) = 100
Second loop: number = number (100) * number(100) = 10.000

Just a bit change, considering that 0^(a) has sense for a > 0 (and it's not 0)

Code:

int main()
{
	double num;
	double onum;
	double pow;
	cout << "Enter number: ";
	cin >> num;
	cout << "Enter power: ";
	cin >> pow;
	if (num == 0)
	{
                if (pow>0)
                {
                        cout << "Ehi! I cannot do that! " << endl;
                        return 1;
                }        
		// this is useless: num = 0;
	}
	else
	{
		onum = num;
		if (pow > 0)
		{
			for (; pow > 1; pow--) 
			{
				num *= onum;
			}
		}
		else if (pow == 0) 
		{
			num = 1;
		}
		else if (pow < 0)
		{
			for (; pow < 1; pow++)
			{
				num /= onum;
			}
		}
	}
	cout << "Result is " << num << endl;
	return 0;
}

0^X = 0. What are you implying?

Originally Posted by Elysia

0^X = 0. What are you implying?

:-o

0^(-3) = 1/(0^3)= 1/0 = indeterminate
0^0 = indeterminate

Depends on your calculator:

Windows Calc says:
0^0 = 1 (Which is false)
0^(-3) = Invalid

Powercalc says:
0^0 = Invalid
0^(-3) = 0

My ti calc says:
0^0 = Invalid
0^(-3) = Invalid

Still, the code doesn't check for division by 0.

Code:

int main()
{
	double num;
	double onum;
	double pow;
	cout << "Enter number: ";
	cin >> num;
	cout << "Enter power: ";
	cin >> pow;
	if (num == 0)
	{
		if (pow <= 0)
		{
			cout << "Invalid number / power combination.\n" << num << " ^ " << pow << ": Invalid operation!\n";
			return 1;
		}
		num = 0;
	}
	else
	{
		onum = num;
		if (pow > 0)
		{
			for (; pow > 1; pow--) 
			{
				num *= onum;
			}
		}
		else if (pow == 0) 
		{
			num = 1;
		}
		else if (pow < 0)
		{
			for (; pow < 1; pow++)
			{
				num /= onum;
			}
		}
	}
	cout << "Result is " << num << endl;
	return 0;
}

This takes into consideration powers of 0 and negative when number is 0.