Default and named parameters for C++ functions

In C, function parameters can be set to default values, simplifying function calls and improving code readability. Additionally, C 11 introduces named parameters, which enhance code readability and flexibility by allowing parameter values ​​to be specified using parameter names at function call time: Default parameters: Use the equal sign (=) to specify parameter default values. Named parameters: Use a colon (:) to separate the parameter name and value to specify the parameter name when the function is called.

Default and named parameters of C functions

In C, function parameters can have default values, which can simplify function calls and make the code more Easy to read. Additionally, C++11 introduced named parameters, allowing parameter names to be specified at function call time.

Default Parameters

To set a default value for a function parameter, follow the parameter type with an equal sign (=) and a default value. For example:

int sum(int a, int b = 0) {
  return a + b;
}

In this example, the default value of the b parameter is 0. If a value for b is not specified when calling the function, the default value of 0 will be used.

Advantages:

• Simplifies function calls as it allows optional parameters to be omitted with default values.
• Improves code readability because the parameters of a function and their default values ​​can be easily identified.

Named parameters

C 11 introduces named parameters, allowing parameter values ​​to be specified by their names when a function is called. The syntax is to use : to separate parameter names and values. For example:

int sum(int a, int b = 0) {
  return a + b;
}

int main() {
  int result = sum(b: 5, a: 3);  // 使用命名参数
  return 0;
}

In the above example, the result variable will contain 8 because the a parameter is set to 3 and the b parameter is specified via a named parameter is 5.

Advantages:

• Improves code readability because it makes it clear which parameter value is associated with which parameter name.
• Allows more flexible function calls when the order of parameters is not important.
• Parameter values ​​can be easily exchanged without modifying the function signature.

Practical case

Consider a function that calculates the area of ​​a circle:

double calcArea(double radius) {
  return 3.14159 * radius * radius;
}

Using default parameters, we can allow the radius parameter to have a default value 1.0:

double calcArea(double radius = 1.0) {
  return 3.14159 * radius * radius;
}

Now we can call functions with default values ​​or override them with named parameters if needed:

double area1 = calcArea();  // 使用默认半径 1.0
double area2 = calcArea(radius: 5.0);  // 使用命名参数指定半径

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