In this paper we analyze statistically the efforts for C++ program modification which is needed by a given requirement change during the prototyping development of a certain GUI application. In the analysis we consider both C++ program $P$ to be updated and the resultant C++ program $P'$, and discuss the correlation between the values {\bf M}$(P)$ of the Object-Oriented metrics obtained from $P$ and the efforts {\bf E}$(P')$ needed to produce $P'$. According to the definitions of {\bf M}$(P)$ and {\bf E}$(P')$, we present two approaches in this paper. In the first approach, we take {\bf M}$(P)$ as the value obtained by applying the metrics to the whole source code $P$ and {\bf E}$(P')$ as the lines of codes({\bf LOC}) that are actually modified or created, respectively. However, the experimental result cannot show strong correlation between {\bf M}$(P)$ and {\bf E}$(P')$. Based on the analysis results of the first approach, we propose the second approach to consider the object-oriented properties more directly. The analysis process consists of following three steps: 1) take only the classes in $P$, classify them according to the MVC paradigm originally for Smalltalk their functions, and then evaluate {\bf M}$(P)$ for the classified classes, 2) in order to evaluate the efforts for code modification, define {\bf E}$(P')$ as the heuristic value which is calculated empirically from the numbers of methods and members created or modified, and 3) analyze the relationship between the values of {\bf M}$(P)$ on the classified classes in $P$ and the values of {\bf E}$(P')$ on the source codes in $P'$. From the experimental result, we can prove there exists a high correlation between them.