update usage document

BWLserver/server.cc

 #include "server.hh"
 
-#define USEAGE                                                                               \
-    "usage: bwl-server [options]" << std::endl                                               \
-                                  << "The options contains:" << std::endl                    \
-                                  << "\t-h | --help\tTo print this document." << std::endl   \
-                                  << "\t-v | --version\tTo print version data." << std::endl \
-                                  << "\t-c | --card\tTo choose which video card to use(card 0 as default)." << std::endl
+#define USEAGE                                                                                    \
+    "usage: bwl-server [options] [args]" << std::endl                                             \
+                                         << "The options contains:" << std::endl                  \
+                                         << "\t-h --help\tTo print this document." << std::endl   \
+                                         << "\t-v --version\tTo print version data." << std::endl \
+                                         << "\t-c --card\tTo choose which video card to use(card 0 as default)." << std::endl
 
 int main(int argc, char **argv)
 {
@@ -14,20 +14,21 @@ int main(int argc, char **argv)
     //解析命令行参数
     for (int i = 0; i < argc; i++)
     {
-        if (std::string(argv[i]) == "-c" || std::string(argv[i]) == "--card")
+        std::string arg(argv[i]);
+        if (arg == "-c" || arg == "--card")
         {
             i++;
             monitor_device = argv[i];
         }
 
-        if (std::string(argv[i]) == "-v" || std::string(argv[i]) == "--version")
+        if (arg == "-v" || arg == "--version")
         {
             std::cout << "Bad WayLand " << BWL_VERSION << std::endl
                       << "Bad Wayland Server " << BWLS_VERSION << std::endl;
             exit(0);
         }
 
-        if (std::string(argv[i]) == "-h" || std::string(argv[i]) == "--help")
+        if (arg == "-h" || arg == "--help")
         {
             std::cout << USEAGE;
             exit(0);