option *longopts, int *longindex);
函数功能:解析长选项形参.
struct option {
const char *name; 表示要解析的长选项字符串...(int argc, char * const argv[],
const char *optstring,
const struct option *longopts.../a.out -a 123 -b 456 -c 789 -v
c=getopt(argc,argv,"a:b:c:v?").../a.out -a 123 -b 456 -c 789 -v
c=getopt_long(argc,argv,"a:b:c:v?".../a.out -a 123 -b 456 -c 789 -v
c=getopt_long_only(argc,argv,"a:b:c:v?"