Array in Java '\0' ?

[Jack_Tauson_Sr]

Does character array in java has '\0' by default in the end?

For example:

char[] ch = {'t', 'h', 'e', ' ', 'd', 'o', 'g', ' ', ' ', ' ', ' ', ' ', ' '};

The Length of above character arrays is 13. So, if I want to start from backwwards then can I initialize a variable calles, newlength = '\0' and start working
backwards?

Please clarify.

Thanks

[JosAH]

Java is not C nor C++; Java doesn't use the '\0' character to indicate the end of string ('end of char array' actually in C and C++). Java keeps a 'length' field for arrays so it can do bound checking behind the scenes.

kind regards,

Jos

[Jack_Tauson_Sr]

Thanks for your reply. Actually, I'm confused with the following program which has "str[newLength] = '\0';" . Why '\0' is mentioned here?

The following program is replacing all the spaces in the strigng with '%20'.

Please explain.

================================================== ================================================
public class Test {
public void replaseSpaces(char[] str, int length) {
int spaceCount = 0, newLength = 0, i = 0;

for(i = 0; i < length; i++) {
if (str[i] == ' ')
spaceCount++;
}

newLength = length + (spaceCount * 2);
str[newLength] = '\0';
for(i = length - 1; i >= 0; i--) {
if (str[i] == ' ') {
str[newLength - 1] = '0';
str[newLength - 2] = '2';
str[newLength - 3] = '%';
newLength = newLength - 3;
}
else {
str[newLength - 1] = str[i];
newLength = newLength - 1;
}
}
System.out.println(str);
}

public static void main(String[] args) {
Test tst = new Test();
char[] ch = {'t', 'h', 'e', ' ', 'd', 'o', 'g', ' ', ' ', ' ', ' ', ' ', ' '};
int length = 6;
tst.replaseSpaces(ch, length);
}
}

================================================== ================================================== =

[JosAH]

That's the 'mechanical' way of doing things in Java; the following snippet replaces spaces with "%20" in a String:

String myString= "the dog and   the cat";
myString= myString.replaceAll("\\s", "%20");
System.out.println(myString);

kind regards,

Jos

[Jack_Tauson_Sr]

Thanks for your answer but could you also explain my question pertaining to my program mentioned above?

[JosAH]

Thanks for your answer but could you also explain my question pertaining to my program mentioned above?

You mean an explanation of that program? It is incorrect; try to run it and see for yourself.

kind regards,

Jos

[Tolls]

Ask whoever wrote it.
Because I suspect they simply took a C program and rewrote almost word for word into Java, without actually knowing what they were doing.

[Jack_Tauson_Sr]

I didn't mean explanation of my program. The program is running perfectly fine:

I repeat my question once again pertaining to the program I mentioned above:
"Actually, I'm confused with the following program which has "str[newLength] = '\0';" . Why '\0' is mentioned here? "

Please explain.

I hope this clarifies my question.

[Tolls]

And as I said, ask whoever wrote it about why they thought it was useful.
As far as I can make out it's not.

[JosAH]

I didn't mean explanation of my program. The program is running perfectly fine:

How strange; when I tested it the output was "the%20do" (plus an invisible '\0' character and a bunch of trailing spaces).

kind regards,

Jos

[Jack_Tauson_Sr]

Actually, the value of length should be 7 instead of 6. Then you will get "the%20dog" as your output.

As we discussed that java doesn't' support "\0", then how come this program is not throwing any error? How come it's running fine even though chances are there that someone who wrote the program copied it from C language.

Please comment on this.

Thanks

[Tolls]

No.
It's not "it doesn't support it".
It's "it doesn't do anything with it".
'\0' is a valid character. It just doesn't mean "EOS".