char *a,*p;

    a = strtok( str, " ");
    f.push_back(a);

    if( (p = strtok(  0 , " " )) !=  0  ){
      param.insert( std::pair<std::string,std::string>(a,p) );
    }

All versions of the C run-time libraries.
Example
// crt_strtok.c
/* In this program, a loop uses strtok
 * to print all the tokens (separated by commas
 * or blanks) in the string named "string".
 */

#include <string.h>
#include <stdio.h>

char string[] = "A string\tof ,,tokens\nand some  more tokens";
char seps[]   = " ,\t\n";
char *token;

int main( void )
{
   printf( "Tokens:\n" );
   /* Establish string and get the first token: */
   token = strtok( string, seps );
   while( token != NULL )
   {
      /* While there are tokens in "string" */
      printf( " %s\n", token );
      /* Get next token: */
      token = strtok( NULL, seps );
   }
}
Output
Tokens:
 A
 string
 of
 tokens
 and
 some
 more
 tokens