由于大多数计算机无法容纳1000个数字的整数，因此您将不得不对输入进行字符串操作或使用 Big数字库.让我们尝试前者.

Since most computers can't hold an integer that is 1000 digits, you will either have to operate on the input as a string or use a Big Number library. Let's try the former.

当将输入视为字符串时，每个数字都是一个介于'0'到'9'(含)范围内的字符.

When treating the input as a string, each digit is a character in the range of '0' to '9', inclusive.

因此，这归结为计数字符:

So, this boils down to counting characters:

std::string text;
cin >> text;
const unsigned int length = text.size();
unsigned int digit_count = 0;
for (i = 0; i < length; ++i)
{
  if (!std::isdigit(text[i]))
  {
    break;
  }
  ++digit_count;
}
cout << "text has " << digit_count << "digits\n";