加急请教一道QB的题
DECLARE FUNCTION c (a AS INTEGER, b AS INTEGER) PRINT c(6, 4)
FUNCTION c (a AS INTEGER, b AS INTEGER)
IF ((a = b) OR (b = 0)) THEN
c = 1
ELSE
c = c(a - 1, b - 1) - c(a - 1, b)
END IF
END FUNCTION
运行结果为:____________________
结果为7,但不会算,这道题中c = c(a - 1, b - 1) - c(a - 1, b)到底是什么意思,请能详细说说步骤,多谢了.