Syntax and usage of C++ function templates?

Function templates are tools for writing functions that can be applied to different data types. By specifying type parameters, you can create a function template and use the template to instantiate a function of a specific data type. For example, you can create the max() template function to get the larger of two values ​​and use max(10, 20) or max(3.14, 2.71) to easily find the maximum value of an integer or floating point number . Alternatively, you can use the swap template function to swap two values, for example swap(a, b) to swap two integer variables.

C Function Templates: Syntax and Usage

Function templates are powerful tools in C that allow you to write functions that can be used in different Data type functions. This avoids writing duplicate code for each data type.

Syntax

The function template has the following format:

template <typename T>
returnType function_name(parameters) {
  // 函数体
}

Where:

• ## means this is a function template and T is the type parameter.
• returnType is the type returned by the function.
• function_name is the name of the function.
• parameters is the parameter list of the function.

How to use

To use function templates, you need to specify type parameters. For example, the following code uses a template to create a

max() function to find the maximum of two integers:

template <typename T>
T max(T a, T b) {
  if (a > b) {
    return a;
  } else {
    return b;
  }
}

You can use the

max() function in the following ways ：

int max_value = max<int>(10, 20); // 20
double max_value = max<double>(3.14, 2.71); // 3.14

Practical case: exchange function

The following is a practical case using function template to implement a function that exchanges two values:

template <typename T>
void swap(T &a, T &b) {
  T temp = a;
  a = b;
  b = temp;
}

Use:

int a = 5;
int b = 10;
swap(a, b);
cout << "a: " << a << endl; // 输出 10
cout << "b: " << b << endl; // 输出 5

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