Parsing and priority of C++ function overloading

Function overloading allows the creation of multiple functions with the same name but different parameter lists. Resolution: To define multiple functions with the same name into the same namespace, each overload must have a unique parameter list. Priority: When selecting a function to be called, the compiler performs matching according to the following priorities: exact match, standard conversion, user-defined conversion, and an error will be reported if the match fails.

Parsing and priority of C function overloading

Function overloading is a powerful feature in C, which allows users with the same name but different Multiple functions with parameter lists to populate the namespace. This overloading feature provides extensive opportunities for flexibility, code readability, and maintainability.

Parsing

Function overloading involves defining multiple functions with the same name into the same namespace. Each overloaded function must have a different parameter list, either in number or type, to distinguish them.

Priority

When an overloaded function is called, the compiler determines the specific function to call based on the parameter types and number. The priority rules are as follows:

• Exact match: If the parameter list of a function overload exactly matches the parameter list given when calling, it will be called first.
• Standard conversions: If an exact match is not found, the compiler will try to apply a standard conversion (for example, promoting an integer to a floating point number) to make the argument match that of one of the overloads List matches.
• User-Defined Conversions: If standard conversions are not possible, the compiler will try to apply any user-defined conversion functions to make the parameters match the parameter list of one of the overloads.
• Failure: If a matching overloaded function cannot be found, the compiler will issue an error.

Practical Example

Consider the following code snippet, which shows how function overloading can be used to print data in different ways:

#include <iostream>

void print(int x) {
  std::cout << "int: " << x << std::endl;
}

void print(double x) {
  std::cout << "double: " << x << std::endl;
}

int main() {
  int a = 5;
  double b = 3.14;
  print(a); // 调用第一个重载
  print(b); // 调用第二个重载
}

Output:

int: 5
double: 3.14

In this example, we define two print function overloads, one for integers and another for floating point numbers. When the first print is called, the compiler finds an exact match, so print(int) is called. Similarly, when the second print is called, an exact match is found, so print(double) is called.

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