This sentence y 1 = FAC (n, x 1, p 1, p2); Is to pass an integer data, a floating point data and two arrays to the subfunction, and the subfunction has a return value, so y 1 receives the return value of the subfunction. for(I = 0； I & ltn；; i++，px++，py++){ x[I]= * px； y[I]= * py； This sentence is to traverse two arrays passed from the main function to the sub-function and assign their values to the other two arrays. I hope I can help LZ to adopt it.