adding numbers that user enters as a single string

Hi all. I've been busting my head for last two days with this problem. It should be fairly simple but since I'm a begginer it's rather confusing. I need to make a program that asks user to enter a number (let's say 34678) and then to output sum of those individual numbers (in this case that should be 28). I came up with this code that I tought will work but...

Code:

#include <iostream.h>
#include <stdlib.h>

void main()
{
 char *num1 = "", *nume;
 double lnum = 0, numt;
 int i = 0;
 cout << "Enter number: ";
 cin >> num1;
 while (num1[i])
 {
  char *tt = num1[i];
  lnum = strtod(tt, &nume);
  numt = (numt + lnum);
  i++;
 }
 cout << numt;
}

Please help. Cheers.

You could try this

Code:

#include <iostream.h>
#include <stdlib.h>

void main()
{
 string num1; 
 int result=0;
 cout << "Enter number: ";
 cin >> num1;
 for(int i=0;i<num1.length();i++){
   if(num1[i]>='0' && num1[i]<='9'){
     result+=(num1[i]-48);//subtract 48 to convert from ascii value
   }//end if
 }//end for   
 cout << result;

To make it more portable I would go for this

Code:

     result+=(num1[i]-'0');

'0' is not necessarily 48 but it is shure that the numbers 0..9 appear in sequence in any character encoding.
Kurt

Originally Posted by ZuK

To make it more portable I would go for this

Code:

     result+=(num1[i]-'0');

'0' is not necessarily 48 but it is shure that the numbers 0..9 appear in sequence in any character encoding.
Kurt

Good point. Small oversight when writing the code in under 5 minutes. I wasn't looking to make sure it was "perfect" just that it ran. It was something just to give him and idea.

Originally Posted by dnysveen

Good point. Small oversight when writing the code in under 5 minutes. I wasn't looking to make sure it was "perfect" just that it ran. It was something just to give him and idea.

I didn't mean to correct you just to add some thought. ( I think it is quite easy to improve a solution. Much harder to come up with one in the first place ).
Kurt

> void main()
Not to mention that main returns an int.

Originally Posted by Salem

> void main()
Not to mention that main returns an int.

I figured he knew how to end his main function. Geeez people

Zuk I understand. I always like to have everything optimized and working the best way. I knew really thought of using -'0' but I do understand now. Thanks for the insight.

Damn it. I knew I was close. I actualy tought of doing -48 thingie but I also tought that there is implemented function for that and that I could use it instead. Thank you for your quick reply. Cheers

Originally Posted by metalinspired

Damn it. I knew I was close. I actualy tought of doing -48 thingie but I also tought that there is implemented function for that and that I could use it instead. Thank you for your quick reply. Cheers

If you used a char array you could use the atoi function which converts character numbers to integer values. I think there would be less overhead subtracting 48 or '0' because you are not making a function call, which takes overhead.

Originally Posted by dnysveen

If you used a char array you could use the atoi function which converts character numbers to integer values. I think there would be less overhead subtracting 48 or '0' because you are not making a function call, which takes overhead.

Good point about function call. How ever atoi (just like strtod or strtol) won't work here. Not sure why but I think it is becouse I'm trying to convert single char to int and they only work with strings. Am I correct? I might be babling total nonsense here but hey nobody was born with knowledge of c++

You could use stringstreams. More C++ish. You can read the int value(s) from the string as if it were an input stream.