Add argument parsing in argparse.cpp

Implement argument parsing for command line inputs.

Author: TimGoTheCreator

argparse/argparse.cpp

@@ -0,0 +1,30 @@
+#include "argparse.hpp"
+#include <iostream>
+#include <stdexcept>
+
+namespace next {
+
+Arguments parse_arguments(int argc, char** argv)
+{
+    if (argc != 5) {
+        std::cerr << "Usage: next <initial.txt> <dt> <dump_interval> <vtk|vtu>\n";
+        std::exit(1);
+    }
+
+    Arguments args;
+    args.input_file = argv[1];
+    args.dt = std::stod(argv[2]);
+    args.dump_interval = std::stod(argv[3]);
+
+    std::string fmt = argv[4];
+    if (fmt == "vtu") args.use_vtu = true;
+    else if (fmt == "vtk") args.use_vtu = false;
+    else {
+        std::cerr << "Format must be 'vtk' or 'vtu'\n";
+        std::exit(1);
+    }
+
+    return args;
+}
+
+}