在 g++ 3.2.3 沒有問題
可是在g++ 3.3.1 會有下面的錯誤

錯誤訊息:

g++ fplan.cpp -c -g -O2 -DNDEBUG
fplan.cpp: In member function `double FPlan::calcWireLength()':
fplan.cpp:272: error: `assert' undeclared (first use this function)
fplan.cpp:272: error: (Each undeclared identifier is reported only once for each function it appears in.)
fplan.cpp: In member function `void FPlan::list_information()':
fplan.cpp:326: error: `assert' undeclared (first use this function)
make: *** [fplan.o] Error 1

請知道的大大解答一下 ... >"<