无符号函数可使用任何数字返回数字

Question

I'm working on an exercise where I have to program an unsigned function in C++ --- The function has returned the number of digits in num and must work on any number.

The issue  --- when I do unsigned num is greater than 10 digits, it still 
shows 10 as the answer.  what am I doing wrong?


unsigned numDigits(unsigned num)  
{
if (num == 0)
return 0; 
return 1 + numDigits(num / 10); 
return (num);
}

int main()
{
unsigned num = 12345678901;
cout << "Number of Digits: " << numDigits(num);
}

Answer 1

unsigned size is:

0 to 65,535 or 
0 to 4,294,967,295 (10 digits)

So change your funtion into:

unsigned numDigits(long long unsigned num)

A cheat solution to your problem is also:

std::string dig = std::to_string(num);
std::cout << dig.size();

Answer 2

 unsigned getNumDigits(long long unsigned num)
 {
      if (num < 9 )
          return 1;
       return 1 + getNumDigits(num / 10 );
 }

@ram , thx for pointing out. Max guaranteed unsigned value is 65535 . Accomodating values more than this will need a bigger (value accomodating) type. Max unsigned value is possible with long long unsigned . A value 0 also mean 1 digit hence comparison against 9 .