if((fp=fopen("date.txt","w"))==NULL) { printf("File open error!\n"); exit(0);能不能解释下什么意思,

if((fp=fopen("date.txt","w"))==NULL) { printf("File open error!\n"); exit(0);能不能解释下什么意思,
if((fp=fopen("date.txt","w"))==NULL) { printf("File open error!\n"); exit(0);能不能解释下什么意思,

if((fp=fopen("date.txt","w"))==NULL) { printf("File open error!\n"); exit(0);能不能解释下什么意思,
if((fp=fopen("date.txt","w"))==NULL) //如果不能打开文件date.txt,则
{
printf("File open error!\n");// 显示“File open error!(文件打开错误)”
exit(0);//并退出程序
}