Why are my Char * values not equal, if I'm giving them the same value?

[keanedawg]

These two values are set to the exact same thing basically, but for some reason, crate != "0 HEAD".

  char crate[7] = "0 HEAD";

	if (crate == "0 HEAD")
		cout << "It Works!"; // This if statement will fail
	cout << endl;

I've tried using consts

My crate[] has an equal capacity to "0 HEAD"

What is wrong?

Thanks!

[Disch]

The solution: Use strings:

#include <string>

//...
string crate = "0 HEAD";

if(crate == "0 HEAD")
    cout << "Now this will work";

Strings are all around safer and less error prone than char arrays.


As for the reason why this doesn't work with char arrays -- the language does not support comparison of arrays. So when you do a == comparison with a char array, it's actually comparing pointers and not the contents of the actual string data. So you are comparing a pointer to your 'crate' array, so a pointer to where the "0 HEAD" string exists inside the executable. Those pointers are going to be different, which is why it fails.



EDIT:

If, for whatever reason, you don't want to use strings, you can use strcmp:

#include <cstring>

//...
char crate[] = "...";

if( strcmp(crate,"...") == 0 )
    cout << "The strings match";

But really... just use strings.

[kbw]

To add to what Disch said above, the C language added types char (for a byte), int (for a machine word), short int (for a smaller integral type), long int (for a longer integral type), and float and double (for possible hardware supported floating point types) to its predecessor, a language called B. long long and long double were added to a later revision of the language to offer better support to more capable hardware.

Note there are no strings! These were hacked in with arrays of chars. So when you write:

   char str["hello"];

The C language reserves 6 bytes and fills them with 'h', 'e', 'l', 'l', 'o', '\0'. The C runtime library has a whole bunch of functions that support this zero terminated (ASCIIZ) string; strcat, strcpy, strcmp, the %s in printf, and so on.

C++ inherited this stuff from C. But you really should use the standard string class. It avoid all the problems such as the you've run into.

[keanedawg]

OK. That was super helpful. Thanks guys!