ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]

[siid14]

I got a warning as you can read from the title.
Precisely this is this line that is affected :

 Rectangle(double, double,
               char *);

After some research I got to know that to fix it I should do the following :

 Rectangle(double, double,
              const char *); // I add the "const" 

Can you give me your own explanation of the warning? I fixed the issue without really understanding that's why.

[jlb]

The problem is not in the lines that you're showing, the problem is how you're calling the function. It appears that you're calling the function with a "string literal" (a constant char*), ie Rectangle(1.0, 2.9, "THIS IS THE VALUE YOU'RE PASSING").

[siid14]

Why I shouldn't do it? and why const char * fix it then?

[jlb]

and why const char * fix it then?

When you add the "const" you are informing the compiler that the function will not try to modify the variable. Remember that you can never modify a "string literal". That pointer can be and usually is pointing to the "Code" segment, which is not writable, hence the need for a const char *.

Why I shouldn't do it?

Do what, exactly? In this instance the compiler won't let you pass a "string literal" via a non-const char pointer, hence the error message.

[jonnin]

you can ugly it up and do it with S.

void foo(const char * cp)
{
  cout << cp << endl;	
}
int main()
{
	foo(("text"s).c_str());

if you are not allowed to use this, you have to clunk:
copy the constant into a variable, and pass the variable to the function, or better, get rid of the constant:
char passme[] = "constant text";
foo(passme); //ok