Thread: Can I create a fileheader using printf?

Originally Posted by Subsonics

How come? If I create an array to store 5 chars is there another way of doing it? I did like this

Code:

char array[5];

Yes, that allows 5 characters to be stored. I think tabstop was referring to your pointer variable, but I'm not sure.

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Mats

Originally Posted by matsp

But a string in C is a sequence of characters that end with a zero - so pointer to char will point to the FIRST of those characters. In the case of "var" in your code, it will be stored somewhere in the program's memory as a sequence of four characters, 'v', 'a', 'r', '\0' - where this is stored is entirely up to the compiler, but generally strings are (nowadays) stored in a read-only data part of your executable file, and loaded into memory just like the code and any pre-initialized data.

Note that "char *var" in itself does not allow even ONE character to be stored. It is a place where you can store the ADDRESS of a character - when you initialize that string with "var", it is given the address that the compiler put those characters in.

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Mats

Ok, thanks for clarifying Mats.

Whats your oppinion about the use of char pointers to point to a complete string? Is it considered kosher generally or is it best avoided?

Originally Posted by Subsonics

Ok, thanks for clarifying Mats.

Whats your oppinion about the use of char pointers to point to a complete string? Is it considered kosher generally or is it best avoided?

Char pointers that point to constant strings is fine (generally speaking - however, for the structure you described in the initial post here, you DO need to have a char array). You should really use "const char *var = "Some string";" - that way the compiler will tell you if you try to modify such a string - which will most likely cause some sort of problem - strange results later on or a crash.

Char pointers to variable content is more complex, as you need to somehow allocate memory, and both that and char arrays requires that you know the maximum length of the final content (and that you validate that you are not going beyond that maximum length, as that will store data into "something elses memory" which leads to corrupted data content and/or a crash - or if you are really "lucky" crash the program directly as you go beyond the limit).

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Mats

Thanks for the help guys. Mats I have updated my code to use arrays instead of pointers now and it seems like a good habit to use 'const char' when using pointers this way as you mentioned, thanks.