Transformation from char to float

There is the function in Delphi.
function StrToFloat(const S: string): Extended;

I think that there is the same function in BCB

One simple way woul dbe to use strchr() to find the first comma, then strchr() from there+1 to find the nexxt one,
then strncpy to extract the number to another string variable, then sscanf or atof() on that.

Sample from MSDN:

/* SSCANF.C: This program uses sscanf to read data items
 * from a string named tokenstring, then displays them.
 */

#include <stdio.h>

void main( void )
{
   char  tokenstring[] = "15 12 14...";
   char  s[81];
   char  c;
   int   i;
   float fp;

   /* Input various data from tokenstring: */
   sscanf( tokenstring, "%s", s );
   sscanf( tokenstring, "%c", &c );
   sscanf( tokenstring, "%d", &i );
   sscanf( tokenstring, "%f", &fp );

   /* Output the data read */
   printf( "String    = %s\n", s );
   printf( "Character = %c\n", c );
   printf( "Integer:  = %d\n", i );
   printf( "Real:     = %f\n", fp );
}

Output
String    = 15
Character = 1
Integer:  = 15
Real:     = 15.000000

In addition to sscanf, atof will convert a pointer to a C-style string (char * at a null-terminated string). You can use grg99's suggestion to find the beginning of the string you want to convert and then call atof:

char * theLine;
// you read the value into theLine here
const char * comma;
comma = strchr(theLine, ',');
++comma;
float value = atof(comma);


Hope this helps, -bcl

Try

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

using namespace std;

void main () {

    float f;
    char* pc;
    string s;
    stringstream ss;

    ss << "$GPGGA,11111.11,...";

    getline ( ss, s, ','); // extract 'til 1st ','

    cout << s << endl;

    getline ( ss, s, ','); // extract 'til 2nd ','

    cout << s << endl;

    f = (float) strtod ( s.c_str (), &pc); // convert to 'float'

    cout << f << endl;
}

Or try this:

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

using namespace std;

void main () {
  double d;
  string val("$GGG-1111.11TZR$");
  size_t pos = val.find_first_of("+-0123456789");

  if(pos==string::npos) {//not found
    d = 0.0;
  } else {
//1.Solution => use atof
  d= atof(val.c_str()+pos);

//2.Solution => use stringstream
  stringstream sio;
  sio << val.substr(pos);
  sio >> d;
  }
  cout << "Double: " << d << endl;
}