C language, help me see how to do these two questions

n！is the factorial of n, and its mathematical meaning is n!=1*2*3*4*..The NC language implementation is as follows: (the program is debugged in the Turboc environment) int factorial(int n).

if(n == 1)

return 1;

elsereturn n * factorial(n - 1);

main()

int n,f;

scanf("%d",&n);

f=factorial(n);

printf("%d",f);

int jiecheng(int num).

if(num==1) return 1;When num is 1, 1 is returned, which is the recursive pushout condition, which is num 1.

return num*jiechent(num-1);This function is used again! That's recursion.

Does this involve recursion? I didn't see it.

If the condition in the if statement is to use an equal sign, it is an assignment statement, so if the assignment is greater than 0, the condition is true, that is, the first if is true, and the output is 5When the second condition is reached, since the assignment statement is equal to 0Therefore, if is false, execute the statement after else, i.e. the output is 4

How do you come up with the question, I do it.

a+=a-=a*=a

Known a=6.

1. Deformation: a+=a-=a*=6. Calculate a*=6, which is a=a*6, and the result is a value of 36 and return 36.

2. So it becomes a+=a-=36. Calculate a-=36, i.e. a=a-36, and the result is a value of 0 and return 0.

3. So it becomes a+=0, that is, a=a+0, and the result is a value of 0 and returns 0.

The final answer is 0

Because there is a-=a in it

a = 6

Execute a * = a, which is equivalent to a = a * a, get a = 36, then execute a -= a, which is equivalent to a = a - a, get a = 0, and finally execute a += a, which is equivalent to a = a + a, and get a = 0