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[英]Whats the difference between const int const& and const int& in C++?
[英]Difference between `int* const& x` and `int* const x` in C++
我已经阅读了按值传递、按引用传递和通过常量引用传递(指针)之间的区别,但我不明白后者之间的区别,只是传递一个常量指针。 例如,两者之间有什么区别
int PI = 3;
int* getArg(int* const& x){
x = Π
return x;
}
int main() {
}
和
int PI = 3;
int* getArg(int* const x){
x = Π
return x;
}
int main() {
}
这两者都会导致相同的error: assignment of read-only parameter 'x'
。
如果您清楚按值和按引用传递变量,那么请尝试将复杂类型分解为多个部分以帮助理解正在发生的事情:
using PointerToInt = int*;
using ConstPointerToInt = PointerToInt const;
int* getArg_v1(ConstPointerToInt x) {
x = Π // it's const by value so you're not allowed to change it
return x;
}
int* getArg_v2(ConstPointerToInt& x) {
x = Π // it's const by reference so you're not allowed to change it
return x;
}
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