代碼測試:
void constBeforeFunction(const double* x, const std::array<double, 3>* d_condition, const std::array<double, 3>& s_condition){
*x = 1.0;
d_condition->at(0) = 1;
d_condition->at(1) = 2;
d_condition->at(2) = 3;
s_condition.at(0) = 4;
double t = 0;
x = &t;
return;
}
void constAfterFunction(double* const x, std::array<double, 3>* const d_condition, std::array<double, 3>& const s_condition){
*x = 1.0;
d_condition->at(0) = 1;
d_condition->at(1) = 2;
d_condition->at(2) = 3;
s_condition.at(0) = 4;
s_condition.at(1) = 5;
s_condition.at(2) = 6;
double t = 0;
x = &t;
return;
}
如果const在指針符*和引用符&之前,即第一個示範,則表示該指針内所指向的值是不可修改的,但是指針變量内的位址是可以修改的;
如果const在指針符*和引用符&之後,即第二個示範,則表示該指針變量即位址是不可修改的,但是指針位址上存儲的值是可以修改的;
對于第二種情況,const指針,位址不可修改,但值可以修改,則類似于引用,因為引用的底層實作是const 指針。