Hi,I'm developing a new panel for the FS standard 777, but I can't get a callback function to write the current mach speed preceeded by a "M" to a string, using the MAKE_STRING macro.I'm quite new to programming gauges, earlier programmed in java, php, c++/MFC.This is the callback function:

MODULE_VAR	ap_mach_hold_var= { AUTOPILOT_MACH_HOLD_VAR };FLOAT64 FSAPI cb_string_speed( PELEMENT_STRING pelement ){		//update the module var	lookup_var(&ap_mach_hold_var);		//multiply the current mach speed to something we can use	UINT64 vmach = ap_mach_hold_var.var_value.n*100;	char x[20] = "M. ";	char n[4]  = "";		//format vmach and put the result in n	wsprintf(n, "%3d", (UINT64) vmach);				//concatenate x and n, result should be x="M. xxx"	strcat(x,n);		//put x to the macro this function was called by	pelement->string = x;	//and leave the callback	 	return ap_mach_hold.var_value.n;}

Using this code, the aircraft won't load or the string gives weird output like "

Try this:sprintf(pelement->string, "M. %3.0f", (float)vmach );Doug

Doug,It worked :) Thanks.Bram