Question

QUESTION 15

1. We need to write a function that calculates the power of x to n e.g. power(5,3)=125.

   Which of the following is a right way to define power function?

   ______________________________________________________________

   		int power(int a, int b) { int i=0, p=1; for(i=b;i>=1;i--)   p*=a; return p; } ______________________________________________________________
   		int power(int a, int b) {      int i=0, p=0;      for(i=1;i<=b;i--)            p=p*a;      return p; } ______________________________________________________________
   		int power(int a, int b) {      int i=0, p=1;      for(i=b;i>=1;i--)            a*=p;      return p; } ______________________________________________________________
   		int power(int a, int b) {      int i=0, p=1;      for(i=a;i>=1;i--)            p=p*b;      return p; } ______________________________________________________________

Answer 1

Answer:

The right function that calculates power is--(first function)

int power(int a,int b)
{
int i=0, p=1;
for(i=b;i>=1;i--)
p*=a;
return p;
}

Explanation: Firstly i is initialized to 0 and p to 1.In the for loop i reinitialized to b and until it greater than or equal to 1 and decreases one and The power value which is p=p*a is stored in p variable and finally it returns power value.

Example: power(5,3) Here a=5 and b=3

When the for loop i=3,p=p*a=1*5=5

i=2,p=p*a=5*5=25

i=1,p=p*a=25*5=125

And i=0 and loop exists and returns p which is 125.

The remaining three functions are wrong.

The second function which is--

int power(int a,int b)
{
int i=0, p=0;
for(i=1;i<=b;i--)
p=p*a;
return p;
}

It is wrong every time multiply p which is 0 with a always gives 0 and 0 is returned So,It is WRONG.

The third function which is--

int power(int a,int b)
{
int i=0, p=1;
for(i=b;i>=1;i--)
a*=p;
return p;
}

It is wrong because calculating power value into a variable and returning p variable.

The fourth function which is--

int power(int a,int b)
{
int i=0, p=1;
for(i=a;i>=1;i--)
p=p*b;
return p;
}

It is wrong because we are taking base value as b to calculate power but are taking a.

Hope you understand and like the answer..

Thank you..