Usage of C++ function rvalue reference parameters

In C, the rvalue reference parameter allows a function to obtain a reference to a temporary object without creating a copy. The advantages include avoiding unnecessary copies, improving performance and readability. The syntax is void func(T&& param). Note that rvalue references can only be bound to temporary objects and can only be used within functions.

Usage of C function rvalue reference parameter

In C, the rvalue reference parameter allows the function to obtain a reference to a temporary object. without creating a copy of it. This improves performance and readability.

Syntax:

void func(T&& param);

Among them:

• && represents rvalue reference
• param is Function parameter
• T is of type

Advantages:

• Avoid unnecessary copying
• Improve performance
• Improve code readability

Practical case:

Consider a string that converts to uppercase Function:

#include <iostream>
#include <string>

using namespace std;

void toUpperCase(string&& str) {
  for (char& c : str) {
    c = toupper(c);
  }
}

int main() {
  string input = "hello";
  toUpperCase(input);
  cout << input << endl;

  return 0;
}

In this case, when passing input to toUpperCase, there is no need to copy the string as it is a temporary object. This function will modify input directly, thus avoiding unnecessary overhead.

Output:

HELLO

Notes:

• Only temporary objects can be bound to rvalue reference parameters.
• rvalue references cannot be bound to existing variables.
• rvalue references can only be used in functions, not as class members.

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