c++ i cant understand the difference between const char* and char*

Question

I know you will say its a duplpicate but belive me i read alot of articles about this but i still cant understand what is the diffrence so im giving two examples.
1.

int strlen(const char* string)
{
   int i = 0;
   while (string[i] != '\0')
   {
       ++i;
   }
   return i;
}

2.

int strlen(char* string)
{
   int i = 0;
   while (string[i] != '\0')
   {
       ++i;
   }
   return i;
}

Main:

int main() 
{
    char str[] = "Hello";
    cout << strlen(str) << endl;
}

The second will work and wont get errors while the first wont.

Consider also `char *const`, which is different from other ones. — Sergey, Nov 17 '16 at 18:09
Unless he's included ``, in which case, it's ambiguous with the standard library function. — Benjamin Lindley, Nov 17 '16 at 18:17

score 1 · Accepted Answer · answered Nov 17 '16 at 18:23

1

Case 1: you can not change value of string, it's read-only. It's used to prevent function from changing value of parameter (Principle of least privilege)

Case 2: you can change value of string.

Also, check that link from comments.

answered Nov 17 '16 at 18:23

Stefan Golubović

1,225
1
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No, not correct. You can change the value of `string` in either function. In the first, you cannot change the value of `string[N]` for any given `N`. – Benjamin Lindley Nov 17 '16 at 18:32
That's correct, you can change value of pointer. What I said is `const char * const` – Stefan Golubović Nov 17 '16 at 18:47

c++ i cant understand the difference between const char* and char*

1 Answers1