fp=fopen("e:\\subjectsdel.txt","w"))==NULL是什么意思

fp=fopen("e:\\subjectsdel.txt","w"))==NULL是什么意思 if((fp=fopen("date.txt","w"))==NULL) { printf("File open err if ((fp=fopen("date.txt","r"))==NULL)是什么意思? if ((fp==fopen(filename,"w"))==NULL) 改为 if ((fp=fopen(filena if((fp=fopen("text.txt","ab+"))==NULL)其中ab+啥意思 fp=fopen("SAVE.txt","rb"))==NULL if(fp = fopen("bank_txt","w") == NULL) { printf("can not ope if ((fp=fopen("student.bin","wb"))==NULL) fp=fopen(p, fp=fopen("DATA_KEHU", if((fp=fopen_s("E:\student.txt","wb"))==NULL),这个代码老是提示错误 if((fp=fopen("d=\\jrzh\\example\\stu-list","wb+"))==NULL)中的N