warning: assignment makes pointer from integer without a cast错误
if((in=fopen("read.in","r"))==NULL) 没注意运算符的优先级,导致了warning:assignmentmakespointerfromintegerwithoutacast错误,好久才找出来原语句是这样的:if(in=fopen("read.in","r")==NULL)分析:由于==的优先级高于=,所以会先计算fopen("read.in","r")==NULL