Squashed 'libs/cli11/' content from commit dcbcb47

git-subtree-dir: libs/cli11
git-subtree-split: dcbcb4721dda5dab0a56d9faaaee50e6a30f7758

book/code/intro.cpp

@@ -0,0 +1,15 @@
+#include "CLI/CLI.hpp"
+#include <iostream>
+
+int main(int argc, char **argv) {
+    CLI::App app{"App description"};
+
+    // Define options
+    int p = 0;
+    app.add_option("-p", p, "Parameter");
+
+    CLI11_PARSE(app, argc, argv);
+
+    std::cout << "Parameter value: " << p << std::endl;
+    return 0;
+}