在给函数使用原始变量时,更好的做法是什么:
unsigned long x = 4;
void func1(unsigned long& val) {
val = 5;
}
func1(x);
or:
void func2(unsigned long* val) {
*val = 5;
}
func2(&x);
勒夫:有什么理由选择一个而不是另一个吗?
在给函数使用原始变量时,更好的做法是什么:
unsigned long x = 4;
void func1(unsigned long& val) {
val = 5;
}
func1(x);
or:
void func2(unsigned long* val) {
*val = 5;
}
func2(&x);
勒夫:有什么理由选择一个而不是另一个吗?
当前回答
我的经验法则是:
如果你想对指针进行算术运算(例如,增加指针地址以遍历数组),或者如果你必须传递一个空指针,请使用指针。
否则使用引用。
其他回答
如果你要修改变量的值,你应该传递一个指针。 尽管在技术上传递引用或指针是相同的,但在用例中传递指针更具有可读性,因为它“通告”了函数将更改值的事实。
可以时使用引用,必要时使用指针。 来自c++常见问题:“什么时候应该使用引用,什么时候应该使用指针?”
引用类似于指针,除了不需要使用前缀*来访问引用所引用的值。同样,在初始化对象之后,不能引用另一个对象。
引用对于指定函数参数特别有用。
有关更多信息,请参阅“Bjarne Stroustrup”(2014)的“c++之旅”(A Tour of c++)第11-12页
指针
A pointer is a variable that holds a memory address. A pointer declaration consists of a base type, an *, and the variable name. A pointer can point to any number of variables in lifetime A pointer that does not currently point to a valid memory location is given the value null (Which is zero) BaseType* ptrBaseType; BaseType objBaseType; ptrBaseType = &objBaseType; The & is a unary operator that returns the memory address of its operand. Dereferencing operator (*) is used to access the value stored in the variable which pointer points to. int nVar = 7; int* ptrVar = &nVar; int nVar2 = *ptrVar;
参考
A reference (&) is like an alias to an existing variable. A reference (&) is like a constant pointer that is automatically dereferenced. It is usually used for function argument lists and function return values. A reference must be initialized when it is created. Once a reference is initialized to an object, it cannot be changed to refer to another object. You cannot have NULL references. A const reference can refer to a const int. It is done with a temporary variable with value of the const int i = 3; //integer declaration int * pi = &i; //pi points to the integer i int& ri = i; //ri is refers to integer i – creation of reference and initialization
我的经验法则是:
如果你想对指针进行算术运算(例如,增加指针地址以遍历数组),或者如果你必须传递一个空指针,请使用指针。
否则使用引用。