I need help with looping

[ben2000]

I wrote this to covert the string to double, but I'm having problem fixing the loop so that it goes through all the digits. when I run this it only converts the first which is -42.40000 and stops.

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
main(){
       double result, convert(char s[]);
       char arr[]="-42.4 5 34 66";
       result=convert(arr);
       printf("%f", result);
       getchar();
       }
       
double convert(char s[])
       {
       double val, power;
       int i, sign,pos,c;
       for (i =0; isspace(s[i]); i++) ;
       sign = (s[i] == '-') ? -1 : 1;
       if (s[i] == '+' || s[i] == '-')
       i++;
       for (val = 0.0; isdigit(s[i]); i++)
       val = 10.0 * val + (s[i] - '0');
       if (s[i] == '.')
       i++;
       for (power = 1.0; isdigit(s[i]); i++) 
          {
            val = 10.0 * val + (s[i] - '0');
            power *= 10;
          }
return sign * val / power;

}

[matsp]

Yes, because you only call the "convert" function once, and convert itself converts only the first float in the string.

You have two choices - either iterate over the strings in the main (skip to the next space each time you have converted a number), or build a list of double's in the convert functions. The lattter is probably best done by passing an array and array-size into the function and returning a count of how many you actually got converted.



I would put braces around the "decimal" handling part, so that the for-loop to deal with the decimals is inside the if checking for a '.' in the string.

--
Mats

[ben2000]

I'm a kinda finding figuring out how to implement what you said.

[foxman]

I would put braces around the "decimal" handling part, so that the for-loop to deal with the decimals is inside the if checking for a '.' in the string.

This isn't necessary (like indentation isn't necessary hah, makes thing clearer tough). I'm sure you can easily figure why.

But since i'm already writing things down, this is some kind of proof i'm posting for fun:

double convert(char s[])
       {
       double val, power;
       int i, sign,pos,c;
       for (i =0; isspace(s[i]); i++) ;
       sign = (s[i] == '-') ? -1 : 1;
       if (s[i] == '+' || s[i] == '-')
              i++;
       for (val = 0.0; isdigit(s[i]); i++)
              val = 10.0 * val + (s[i] - '0');

       /* A: s[i] isn't a digit */

       if (s[i] == '.')
       {
              i++;
              /* A: s[i] is something haha */
       }

       else
       {
              /* A: s[i] isn't a digit, that means the condition in the for loop will be false on the first iteration */
       }

       for (power = 1.0; isdigit(s[i]); i++) 
          {
            val = 10.0 * val + (s[i] - '0');
            power *= 10;
          }
return sign * val / power;

}