Thread: Can someone please explain strings to me?

in the String class for java, I believe there is a function .toChar() or something. Well what that does is it turns the String into a char[]

A string in C, is comprised of just an array of characters, there is no class in C.
>Terminated by a NULL character ('\0')
>Without the NULL character, it is just an array of characters, C will not recognize it as a String without the NULL
>Thanks Quzah
if your a beginner to C, try to avoid dynamic strings (strings where you change the size of it)

and go ahead and be wasteful of memory like

Code:

char myStr[256];

and to use strings, you can't just say
myStr = "hi";
there is a function in string.h to assign Literal strings (strings int he quotes) to the character array
prototype:

Code:

int strcpy(char* destination, char* cpyString);

lets say you allocate some memory for a string and then you want to put Hello world in it, you can do this many ways, here are some:

Code:

1:
  char *str = "Hello, World\n";
2:
  char str[] = "Hello, World\n";
3:
  char str[256]; 
  strcpy(str,"Hello, World\n");

just remember that arrays are treated as pointers and similar. Please read the FAQ for more details.

-LC

You will get a lot from
http://cboard.cprogramming.com/searc...der=descending

A string in C, is comprised of just an array of characters

No. This is not a string:

Code:

char foo[3] = { 'c', 'a', 't' };

It has no null terminator, and as such, isn't a string. A string is an array of one or more charactes, terminated by a null. Without the null, it's just an array of characters.

I know you know the difference, but just to clarify for those who don't.

Quzah.

Originally posted by quzah
No. This is not a string:

Code:

char foo[3] = { 'c', 'a', 't' };

It has no null terminator, and as such, isn't a string. A string is an array of one or more charactes, terminated by a null. Without the null, it's just an array of characters.

I know you know the difference, but just to clarify for those who don't.

Quzah.

Of course that is not a string. It is an array of character constants. It would be a string constant if it was a seqence of one or more characters surrounded by double quotes. And then of course if it has the null character at the end (as you mentioned). But technically speaking, a string is an array of characters.

That is because the compiler adds a NULL character at the end of the double quotes, not all compilers do this, older C compilers do NOT do this, you have to add the '\0' at the end.

and a string is NOT technically an array of characters. It is an array of characters with NULL at the end. The standard defines a string as an array of characters that is NULL terminated. In the world of programming, techincalities get sent to /dev/null

in the older C compilers "cat" was illegal to use as a string. "cat\0" was the way you would have to do it. the NULL is VERY important in C, just dont forget the NULL and you will be alright


-LC

im sorry, the point I was trying to make was, that it must be made very clear that there is in fact a NULL character at the end of every standard c string.

and beacuse you don't see the null when you use quotes it must be made very clear (especially to new C programmers) that there is a NULL character.

-LC

>this will aviod buffer overflows (segmentation faults)<

Don't be so sure. strn* functions do not protect agains stupidity :

Code:

int main(void)
{
    char s[5];

    strncpy(s, "A", 10);
}

>NULL character

[NITPICK]
NULL, by its C standard definition, is "an implementation-defined null pointer constant" or "[t]he null pointer constant to which the macro NULL expands".

This may be viewed as mere pedantry -- though it is an FAQ -- but I do think it may be worth pointing out that in C, NULL is implied to be a pointer and not a character. By using "NULL character", it might add to confusion for newcomers to the language, because it can have a distinctly different meaning than "null character", which '\0' represents.
[/NITPICK]