Convert decimal dollar amount from string to scaled integer

Question

"35.28" is stored as a char*. I need to turn it into an integer (35280).

I want to avoid floats. How can I do this?

Answer 1

Minimal basic code:

std::string s = "35.28";
s.erase(std::remove(s.begin(), s.end(), '.'), s.end()); //removing the dot
std::stringstream ss(s);
int value;
ss >> value;
value *= 10;
std::cout << value;

Output:

35280

Online demo : http://ideone.com/apRNP

That is the basic idea. You can work on the above code to make it more flexible so that it can be used for other numbers as well.

---

EDIT:

Here is one flexible solution:

int Convert(std::string s, int multiplier) 
{
   size_t pos = s.find('.');
   if ( pos != std::string::npos)
   {
       pos = s.size() - (pos+1);
       s.erase(std::remove(s.begin(), s.end(), '.'), s.end());
       while(pos) { multiplier /= 10; pos--; }
   }
   else
        multiplier = 1;
   std::stringstream ss(s);
   int value;
   ss >> value;
   return value * multiplier;
}

Test code:

int main() {
      std::cout << Convert("35.28", 1000) << std::endl; //35.28 -> 35280
      std::cout << Convert("3.28", 1000)  << std::endl; //3.28  -> 3280
      std::cout << Convert("352.8", 1000) << std::endl; //352.8 -> 352800
      std::cout << Convert("35.20", 1000) << std::endl; //35.20 -> 35200
      std::cout << Convert("3528", 1000) << std::endl;  //no change
      return 0;
}

Output:

35280
3280
352800
35200
3528

Online Demo : http://ideone.com/uCujP

Answer 2

Remove dot char from string and convert it directly to int

Answer 3

Do you mean stored as a string (char*)? Then you can create your own parser:

int flstrtoint(const char *str) {
    int r = 0;
    int i = strlen(str) - 1;

    while (i >= 0) {
        if (isdigit(str[i])) {
            r *= 10 
            r += str[i] - `0`;
        }
        i--;
    }

    return r;
}

flstrtoint("35.28"); // should return 3528

Answer 4

Remove the dot from the char and then
Simplest but not the best use atoi

See my answer here, for other possible ways.

Answer 5

As Als sais, use atoi, but with a twist, strip the string of the period and convert the result into int using atoi.