diff --git a/dbc.cpp b/dbc.cpp
new file mode 100644
index 0000000..482ed9b
--- /dev/null
+++ b/dbc.cpp
@@ -0,0 +1,44 @@
+#include "dbc.hpp"
+#include <iostream>
+
+void dbc::log(const string &message) {
+  std::cerr << "!!!!!!!!!!" << message << std::endl;
+}
+
+void dbc::sentinel(const string &message) {
+  string err = fmt::format("[SENTINEL!] {}", message);
+  dbc::log(err);
+  throw dbc::SentinelError{err};
+}
+
+void dbc::pre(const string &message, bool test) {
+  if(!test) {
+    string err = fmt::format("[PRE!] {}", message);
+    dbc::log(err);
+    throw dbc::PreCondError{err};
+  }
+}
+
+void dbc::pre(const string &message, std::function<bool()> tester) {
+  dbc::pre(message, tester());
+}
+
+void dbc::post(const string &message, bool test) {
+  if(!test) {
+    string err = fmt::format("[POST!] {}", message);
+    dbc::log(err);
+    throw dbc::PostCondError{err};
+  }
+}
+
+void dbc::post(const string &message, std::function<bool()> tester) {
+  dbc::post(message, tester());
+}
+
+void dbc::check(bool test, const string &message) {
+  if(!test) {
+    string err = fmt::format("[CHECK!] {}\n", message);
+    dbc::log(err);
+    throw dbc::CheckError{err};
+  }
+}
\ No newline at end of file