c++ 中 integer 的第一个和最后一个数字的总和

Question

#include<iostream>
#include<math.h>
int main()
{
  int n,first,last,digits;
  cin>>n;
  last=n%10;
  digits=log10(n);
  first=n/pow(10,digits);
  cout<<first+last;`
}

The above code shows 2 as output for the input 0101 but it should show 1.since 0+1=1.can anyone suggest code in c++?

Answer 1

Your input is 0101 into n. n is an int . So the preceding useless 0 in 0101 is shaved off and you get the correct answer for 101 (1 + 1 = 2). You'll need to use a string if you want to get 1 for 0101.

Answer 2

It's a math, you can expression to get the first (most significant digit) of an integer number:

first = n / static_cast<int>(pow(10, static_cast<int>(log10(n))));