Thread: Here we go again: when to use Malloc and when not?

Originally Posted by django

Does that mean that my second code snipplet is also bad programming, so things like:

Code:

char *p = "so fine";
<...lots of other code...>
p = "even finder";

That will work because all you are doing is changing the address pointed to...

BTW, what compiler are you using... that allows you to mess with changing string literals?

I was not clear I guess. I am reusing a pointer by assigning different string literals to it, is that bad programming?

Originally Posted by django

I was not clear I guess. I am reusing a pointer by assigning different string literals to it, is that bad programming?

Strange... but not evil.

Originally Posted by CommonTater

BTW, what compiler are you using... that allows you to mess with changing string literals?

LCC compiler for windows

Originally Posted by CommonTater

Strange... but not evil.

Ok then, suppose I am writing a function foo, and am testing it in main to see if it works. It takes a *char and does something with it. How would you do this?

Code:

void foo(char *story) {
   ...
   }

int main(void) {

   char *p = "test";
   foo(p);

   p = "another test string";
   foo(p);

   etcetera
}

Originally Posted by django

Ok then, suppose I am writing a function foo, and am testing it in main to see if it works. It takes a *char and does something with it. How would you do this?

Code:

void foo(char *story) {
    printf("%s",story);
   // and absolutely nothing that changes the value of story.
   }

int main(void) {

   char *p = "test";
   foo(p);

   p = "another test string";
   foo(p);

   etcetera
}

Originally Posted by AndrewHunter

You cannot modify string literals, as you have been told over and over again. If you want to modify text you need to store them as C-style strings. See Lesson 9: C-Style Strings.

That's why I asked about his compiler... It should be complaining it's butt off...

Originally Posted by AndrewHunter

You cannot modify string literals, as you have been told over and over again. If you want to modify text you need to store them as C-style strings. See Lesson 9: C-Style Strings.

I did not express myself clearly. I am well aware that string literals cannot be changed. The function does not change them but simply takes them as an input. My point/question was, that I have the same pointer point to different string literals consecutively and whether this is correct use of the 'reused' pointer (which is a variable after all).

Originally Posted by AndrewHunter

Yeah, I know. I don't have any experience with those little C compilers so I am not sure how they are setup, however you would expect some sort of warning.

Could you point out a line in my sample code were your compiler would complain it's bud off?

This line:

Code:

char *p = "test";

should cause warnings, as you are losing const-ness (the right side is "pointer to constant char", while the left side is "pointer to char").

Originally Posted by tabstop

This line:

Code:

char *p = "test";

should cause warnings, as you are losing const-ness (the right side is "pointer to constant char", while the left side is "pointer to char").

Strange, it looks a lot like

Code:

char *pmessage = "now is the time";

which comes straight from Kernighan and Ritchie (2nd edition p.104)

You should be reading a book that dates from after the invention of "const" then.