made an index_of() method for StringValue, which calculates the index of

a char

StringValue.cpp

@@ -37,4 +37,13 @@ StringValue::operator const char*() const
 { return _data; }
 
 size_t StringValue::size() const
-{ return _size - 1; }
+{ return _size - 1; }
+
+size_t StringValue::index_of(char* c) const
+{
+    size_t index = c - _data;   // this is totally safe pointer-arithmetic
+    if (index <= this->size())  // if it is within our data
+        return index;
+    else
+        throw std::invalid_argument("char* not within held data!");
+}

StringValue.h

@@ -28,4 +28,5 @@ public:
     char& operator[](size_t index);
     operator const char*() const;
     size_t size() const;
+    size_t index_of(char* c) const;
 };