The role of const in c++

In C, const is used to declare constants or pointers to constants. Its function is as follows: declare constants to ensure that the variable value is determined at compile time to prevent accidental modification. Declare a pointer to a constant, ensuring that the value pointed to by the pointer cannot be modified. Declare function parameters as constants to prevent parameter values ​​from being modified within the function.

The role of const in C

const is a keyword in C, used to declare constants or pointers Pointer to constant. It has three main functions:

1. Declare constants

const Declare constants, that is, variables whose values ​​are determined at compile time. The syntax is as follows:

<code class="cpp">const data_type identifier = value;</code>

For example:

<code class="cpp">const int my_number = 10;</code>

my_number is now a constant and its value cannot be changed through assignment operations.

2. Declare a pointer to a constant

const can also be used to declare a pointer to a constant, the syntax is as follows:

<code class="cpp">data_type const *identifier = &value;</code>

For example:

<code class="cpp">int my_array[] = {1, 2, 3};
int const *ptr = my_array;</code>

ptr points to the element in my_array, but since ptr is a constant, it cannot change the value pointed to, only Can be read.

3. Function parameters

#const can be used to declare function parameters, indicating that the parameter value cannot be modified within the function. The syntax is as follows:

<code class="cpp">return_type function_name(data_type const parameter);</code>

For example:

<code class="cpp">int sum(int const num1, int const num2) {
  return num1 + num2;
}</code>

In the sum function, num1 and num2 are constant parameters and cannot Change.

Benefits of using const:

• Improve code clarity: Explicitly indicate the constant nature of a variable or pointer.
• Prevent accidental modification: Prevent accidental overwriting of constant values ​​or pointers to constants.
• Improve program security: By preventing modification of constants, the robustness and reliability of the program can be improved.

The above is the detailed content of The role of const in c++. For more information, please follow other related articles on the PHP Chinese website!