What\'s the Difference Between const char* and const char* const?: A Comprehensive Explanation

Const Char Pointer Variants: A Comprehensive Explanation

When working with C , developers encounter different variants of const char pointers, including const char * and const char * const. Understanding the subtle distinctions between these variations is crucial for effective code development.

Examining the Example

Consider the following code snippet:

<code class="cpp">void print_string(const char * the_string)
{
    cout << the_string << endl;
}

int main () {
    print_string("What's up?");
}</code>

In this example, the print_string function takes a pointer to a character, const char *. However, it could have also been defined as const char * const the_string.

Key Differences

The difference between const char * and const char * const lies in their mutability.

• const char * allows you to change the pointer's target (e.g., the_string ) and modify the pointed-to character (e.g., *the_string = 'A').
• const char * const prevents modifications to either the pointer's target or the character it points to.

Suitability for the Example

In the example provided, either const char * or const char * const would be appropriate for the print_string function. However, const char * const is more precise because it prevents accidental modifications within the function.

General Applicability

When choosing between these pointer variants, consider the intended usage:

• char* the_string: Use when you need to change both the target and the pointed-to character.
• const char* the_string: Use when you only need to change the target.
• char* const the_string: Use when you only need to modify the pointed-to character.
• const char* const the_string: Use when you need to preserve both the target and the pointed-to character.

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