C++ function types and usage

There are two types of C functions: pass-by-value functions and pass-by-reference functions. The former passes a copy to the function, the latter passes a reference to the function. The function prototype declares the function name, parameter types, and return value type. Function implementation provides the actual code. Call a function using the function name and argument list. Real-life examples include functions that calculate the length of strings, and demonstrate passing by value and passing by reference.

Types and usage of C functions

Function overview

The function is to Code is grouped into blocks of code that are independent modules. It allows you to reuse code, making your program more readable and maintainable.

Function types

There are two types of functions in C:

• Value passing function: Function A copy of the parameters is passed to the function. Any modifications made to the copy will not be reflected on the original parameters.
• Reference transfer function: Pass the reference of the function parameter to the function. Any modifications to the reference will be reflected on the original parameter.

Function prototype

The function prototype declares the name, parameter type and return value type of the function.

return_type function_name(parameter_list);

For example:

int sum(int a, int b);

Function implementation

Function implementation provides the actual code of the function.

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

Calling a function

Call a function using its name followed by parentheses and a parameter list.

int result = sum(1, 2);

Practical case

The following is a practical case of a function that calculates the length of a string:

// 值传递函数
int string_length(string str) {
  return str.length();
}

// 引用传递函数
void reverse_string(string& str) {
  reverse(str.begin(), str.end());
}

int main() {
  string name = "John Doe";
  int length = string_length(name);
  cout << "Length of the string: " << length << endl;

  reverse_string(name);
  cout << "Reversed string: " << name << endl;

  return 0;
}

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