C Programming - Functions - Discussion

There is no 'main' function. Then, how it's execute?

According to me, it is;

long fun(int num)
{
int i;
/* declare variable i as int.... */

long f=1;
/* declare and initialize variable f as long with value 1 */

for(i=1; i<=num; i++)
f = f * i;

/* for loop is used
Let's take an example...
-> 10 is given as arguments in the function fun...
[First Time]
- > i is initialized with 1 , 1<=10 ,condition true
- > f = 1*1
[Second Time]
- > i is incremented and becomes i = 2 , 2<=10 , condition true
- > f = 1*2 = 2

and further till i = 10, 10<=10 , condition true
- > f = 1* 2*3*4*5*6*7*8*9*10 */

return f;
/* because it returns an float variable .... */
}

Can anyone please explain this?

Very nice.

You can take any value for num. In for loop, the statement written, it will behave like factorial so answer is C. Take any value you will understand.

It gives the correct result, even if we put 0 value then also for loop won't work and we return the value of f and previously it is initialized to 1 and 0!=1.

So it works perfectly fine for 0 value also.

It does not calculate the factorial of all the numbers. 0! is not calculated so None of the above must be the correct answer.

Suppose num=4;

In the program given that
>> f=1
>>for(i=1;i<=4;i++)
f=f*i;
let us evaluate the for loop
step 1: f=1*1=1
step 2: f=1*2=2
step 3: f=2*3=6
step 4: f=6*4=24

IN EACH STEP VALUE OF " f " is saved

So factorial of 4 is 24.

I can't understand.

I don't understand why to use num?