Please add the prototype for your function in the init section of your script. Please see the example below.

/*** Prototype for functions that don't return integers ***/

float atof(char *);

Vuser_init()

{

return 0;

}

The prototype function is an excellent tip. You then have to do something like this:

char strNr[4]; // holds value of price while it is a string
char CStr[100]; // holds the string representation of the float
float i; // unit price as a floating point
float result =0; //

// ---------------------request comes here ------------------------

// copy param to string

strcpy(CStr, lr_eval_string(lr_eval_string(''{corr_param_UnitPrice}'')));

// copy string to floating point. Note you must have the prototype function above
i = atof(CStr);

// Perform the floating point calculation
result = (i * .35) + i;

// store increased price into formatted string
sprintf( strNr, ''%.2f'', result );

// store string in parameter
lr_save_string( strNr, ''corr_param_UnitPrice'' );