String to Dec conversion

[mherald81]

I currently have:

int	converttoint(string strtodec)											
{
	int num,sum=0;
	for(int i=0; i<strtodec.length(); i++)
	{
		switch(strtodec[i])
		{
		case '0': num=0;break;
		case '1': num=1;break;
		case '2': num=2;break;
		case '3': num=3;break;
		case '4': num=4; break;
		case '5': num=5; break;
		case '6': num=6;break;
		case '7': num=7;break;
		case '8': num=8;break;
		case '9': num=9;break;
		case 'A': num=10;break;
		case 'B': num=11;break;
		case 'C': num=12; break;
		case 'D': num=13;break;
		case 'E': num=14;break;
		case 'F': num=15;break;
		}
		sum+=(int)pow(16.0,3-i)*num;
	}
	return sum;
}

Is there another way to do this? Oh and the string value is hex.

[Zaita]

If your string represents a hex array then it'd be difference.

e.g

string someHex = "EDF"; // How I see your method?
// vs
string someHex = 0x41; // Shud be an array of unsigned chars instead. 

If yours is the first case, then the way you have done it will suffice. Although your math is wrong.

int converttoint(string strtodec)                     //function to check if the operand is correct
{
  int num,sum=0;
  for(int i=strtodec.length()-1; i>=0; i--)
  {
    switch(strtodec[i])
    {
    case '0': num=0;break;
    case '1': num=1;break;
    case '2': num=2;break;
    case '3': num=3;break;
    case '4': num=4; break;
    case '5': num=5; break;
    case '6': num=6;break;
    case '7': num=7;break;
    case '8': num=8;break;
    case '9': num=9;break;
    case 'A': num=10;break;
    case 'B': num=11;break;
    case 'C': num=12; break;
    case 'D': num=13;break;
    case 'E': num=14;break;
    case 'F': num=15;break;
    }
    sum += (int)num * pow(16, strtodec.length() - (i+1));
  }
  return sum;
}

[mherald81]

I think I want it as a hex array. This is something I came up with just testing it out. Thanks for the correction on the math.

[Zaita]

Then you wanna use an array of unsigned chars, and the similar math to sum += (int)num * pow(16, strtodec.length() - (i+1)); when iterating through it.

[Zaita]

Cleaner Version:

#include <iostream>
#include <string>
#include <math.h>

using namespace std;

int converttoint(string input)                     //function to check if the operand is correct
{
  int sum = 0;
  for(int i = input.length()-1; i >= 0; i--) {
    // Change Off-Set 
    if ((input[i] >= '0') && (input[i] <= '9'))
      input[i] -= '0';
    else if(toupper(input[i] >= 'A') && (toupper(input[i] <= 'F')))
      input[i] = toupper(input[i]) - 'A' + 10;
    else
      return 0; // Do Some error catching

    sum += (int)input[i] * (int)pow(16, input.length() - (i+1));
  }
  return sum;
}

int main() {
  cout << converttoint("AB") << endl;

  return 0;
}