Advanced usage of reference parameters and pointer parameters in C++ functions

The reference parameters in the C function (essentially variable aliases, modifying the reference modifies the original variable) and pointer parameters (storing the memory address of the original variable, modifying the variable by dereferencing the pointer) have different usages when passing and modifying variables. Reference parameters are often used to modify original variables (especially large structures) to avoid copy overhead when passed to constructors or assignment operators. Pointer parameters are used to flexibly point to memory locations, implement dynamic data structures, or pass null pointers to represent optional parameters.

Advanced usage of reference parameters and pointer parameters in C functions

In C functions, reference parameters and pointer parameters are allowed to be Different ways to pass and modify variables. It is important to understand their differences and use them appropriately.

Reference parameters

Reference parameters are essentially aliases for variables. Any changes made to the reference parameter are reflected in the original variable.

Syntax:

void func(int& ref_param)
{
    ref_param++; // 修改引用参数会修改原始变量
}

Pointer parameters

Pointer parameters store the memory address of the original variable. The original variable can be accessed and modified through the pointer, but a copy is not created.

Syntax:

void func(int* ptr_param)
{
    *ptr_param++ // 通过解引用指针可以修改原始变量
}

Usage scenarios

• ## Reference parameters:

  When you need to modify the original variable within a function
  • Pass a large structure or class object to avoid the overhead of copying
  • Pass the object as a non-const reference to the constructor or assignment operator

• Pointer parameters:

  When you need to flexibly point to different memory locations
  • Implementation Dynamic data structures, such as linked lists
  • Pass a null pointer to indicate optional parameters

Practical case:

Use reference parameters to exchange two numbers

void swap(int& a, int& b)
{
    int temp = a;
    a = b;
    b = temp;
}

Use pointer parameters to access the array

void printArray(int* arr, int n)
{
    for (int i = 0; i < n; i++)
    {
        cout << arr[i] << " ";
    }
    cout << endl;
}

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