added support for negative arguments

Author: Jesse

argparse.h

@@ -92,9 +92,10 @@ class ArgumentParser {
         }
       };
       for (int i = 1; i < argc; i++) {
-        if (std::strlen(argv[i]) == 0) {
+        size_t slen = std::strlen(argv[i]);
+        if (slen == 0) {
           continue;
-        } else if (argv[i][0] == '-') {
+        } else if (slen >= 2 && argv[i][0] == '-' && !isnumber(argv[i], slen)) {
           push_arg();
           if (i == argc - 1) {
             name = &(argv[i][1]);
@@ -220,6 +221,24 @@ class ArgumentParser {
     _trim(s, f);
     return s;
   }
+  static inline bool isnumber(const char *arg, size_t len) {
+    if (std::isdigit(arg[0])) {
+      return true;
+    } else if (len >= 2) {
+      if (arg[0] == '-') {
+        if (std::isdigit(arg[1])) {
+          return true;
+        } else if (len >= 3) {
+          if (arg[1] == '.') {
+            if (std::isdigit(arg[2])) {
+              return true;
+            }
+          }
+        }
+      }
+    }
+    return false;
+  }
 
   std::string _desc;
   std::string _bin;

example.cpp

@@ -48,7 +48,7 @@ int main(int argc, char* argv[]) {
   auto v = parser.getv<double>("v");
   std::cout << "v: ";
   std::copy(v.begin(), v.end(), std::ostream_iterator<double>(std::cout, " "));
-  double sum;
+  double sum = 0;
   for (auto& d : v) sum += d;
   std::cout << " sum: " << sum << std::endl;
   auto f = parser.getv<std::string>("files");