--- a/C++/modules/Ini/Ini.cpp	Tue Nov 03 10:58:44 2015 +0100
+++ b/C++/modules/Ini/Ini.cpp	Tue Nov 03 11:34:46 2015 +0100
@@ -16,7 +16,6 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <cassert>
 #include <cctype>
 #include <cstring>
 #include <iostream>
@@ -139,6 +138,9 @@
 	if (it == end) {
 		throw Error{line, column, "section name expected after '[', got <EOF>"};
 	}
+	if (value.empty()) {
+		throw Error{line, column, "empty section name"};
+	}
 
 	/* Remove ']' */
 	++ it;

--- a/C++/modules/Ini/Ini.h	Tue Nov 03 10:58:44 2015 +0100
+++ b/C++/modules/Ini/Ini.h	Tue Nov 03 11:34:46 2015 +0100
@@ -25,6 +25,7 @@
  */
 
 #include <algorithm>
+#include <cassert>
 #include <exception>
 #include <stdexcept>
 #include <string>
@@ -291,10 +292,12 @@
 	 * Construct a section with its name.
 	 *
 	 * @param key the key
+	 * @pre key must not be empty
 	 */
 	inline Section(std::string key) noexcept
 		: m_key{std::move(key)}
 	{
+		assert(!m_key.empty());
 	}
 
 	/**
@@ -323,22 +326,26 @@
 	 *
 	 * @param key the key
 	 * @return the option
-	 * @throw std::out_of_range if the key does not exist
+	 * @pre contains(key) must return true
 	 */
 	inline Option &operator[](const std::string &key)
 	{
+		assert(contains(key));
+
 		return *find(key);
 	}
 
 	/**
-	 * Access an option at the specified key.
+	 * Overloaded function.
 	 *
 	 * @param key the key
 	 * @return the option
-	 * @throw std::out_of_range if the key does not exist
+	 * @pre contains(key) must return true
 	 */
 	inline const Option &operator[](const std::string &key) const
 	{
+		assert(contains(key));
+
 		return *find(key);
 	}
 
@@ -467,6 +474,7 @@
 	 * Check if a document has a specific section.
 	 *
 	 * @param key the key
+	 * @return true if the document contains the section
 	 */
 	inline bool contains(const std::string &key) const noexcept
 	{
@@ -478,22 +486,26 @@
 	 *
 	 * @param key the key
 	 * @return the section
-	 * @throw std::out_of_range if the key does not exist
+	 * @pre contains(key) must return true
 	 */
 	inline Section &operator[](const std::string &key)
 	{
+		assert(contains(key));
+
 		return *find(key);
 	}
 
 	/**
-	 * Access a section at the specified key.
+	 * Overloaded function.
 	 *
 	 * @param key the key
 	 * @return the section
-	 * @throw std::out_of_range if the key does not exist
+	 * @pre contains(key) must return true
 	 */
 	inline const Section &operator[](const std::string &key) const
 	{
+		assert(contains(key));
+
 		return *find(key);
 	}