DrTrueman / Publications

What does p1-=1 mean? (in OBJ_TREND MQL4 documention example)

I am trying to add trendlines to a chart based on OBJ_TREND in the MQL4 documentation example. https://docs.mql4.com/constants/objectconstants/enum_object/obj_trend Can someone please explain what p1-=1 means in the for loop for ( int i= 0 ;i<v_steps;i++) { //--- use the following value