Pointer to String

[tinu73]

I'm getting started with c and i have the following question:

Within main()

char string[] = "Hallo World";
function(string);

void function(char *str)
{
    printf("%s\n",str);
    char *ptr = str + 5;
    *ptr = '-';
    printf("%s\n",str);
}

Output:
Hallo World
Hallo-World

Why does the program doesn't work if i'm defining:
char *string = "Hallo World";

[ZuK]

Why does the program doesn't work if i'm defining:
char *string = "Hallo World";

This defines str as a string literal, a string constant. The copiler puts it into read only memory.
Kurt

[tinu73]

Thanks for the fast answer! But why the keyword "const" is not required? It seems that char* implicitly declares as const, same as const char[] ="Hallo World", and const char* = "Hello World" doesn't make sense then.

[laserlight]

But why the keyword "const" is not required?

Because there was a time where string literals existed but the const keyword did not, and the powers that be decided that allowing a string literal to be assigned to/to initialise a char* was the right choice, perhaps for backward compatibility.

It seems that char* implicitly declares as const

It doesn't.

[ZuK]

I don't remember exactly. It's some backwards compatibility issue.
Kurt