hello... what can i put when the arduino programming error said like this
You didn't post the actual error
It means that something you did before that point doesn't make sense. My guess is it's:
unsigned int_ //lineSensorvalues[3];
Once you take out the comment you are left with:
unsigned int_
That would declare a variable named "int_" but the line doesn't have a terminating semicolon so it becomes part of the next line:
unsigned int_ const uint16_t lineSensorThreshold = 1000;
That combined line makes no sense so you get an error.