How do i append a null in string?!

I want to create a loop that adds the first value "this" by the command

Code:

strcat(l->value,l->db.param_value.val);

now i want to append a null and move it one more space to the right so i can have

Code:

"this"'\0'"is"'\0'

if i do strcat continuously in a loop it just gives me "thisis", anyone have a suggestion on how to do this ?

Ive tried the statement below it didn't work

Code:

    l->value=  l->value[1 + strlen(l->db.param_value.val)]; AND
       l->db_cmd +=  strlen(l->db.param_value.val) + 1;

Thank you!

The null char '\0' is not equivalent to the space char " ". You do realize this correct? The simplest thing to do is to add another strcat line and append whatever char you actually want to your string.

Well how would anything else know to stop at the second \0 and not the first?

Creating it is easy enough, you just use memcpy() and do all the indexing and counting yourself.

But all the str... functions will just stop at the first \0, regardless of whatever else you may do.

Why do you want a nul character in the middle of your string? You do know that the nul terminator effectively stops all string functions right there, right? That's what denotes the end of a string. strcat just picks up where the end of the string is (the first nul terminator it encounters) and adds the next string right there.

You can't print out a string using any string functions that has embedded nul terminators and expect to get anything past the first nul.


Quzah.

Originally Posted by KMAN999

I want to create a loop that adds the first value "this" by the command

Code:

strcat(l->value,l->db.param_value.val);

now i want to append a null and move it one more space to the right so i can have

Code:

"this"'\0'"is"'\0'

if i do strcat continuously in a loop it just gives me "thisis", anyone have a suggestion on how to do this ?

Assuming you actually want a space char, then you may want to do something like this:

Code:

#include <stdio.h>
#include <string.h>


int main (void) {
  
	char result[30]={0};
	char *string1 = "This";
	char *string2 = "is a line";

	strcat(result, string1);
	printf("%s\n", result);
	strcat(result, " ");
	strcat(result, string2);
	printf("%s\n", result);

	getchar();
        return 0; 
}

Presuming you really do want '\0' and not just a space for whatever reason:

After a strcpy() or stcat() or similiar, there will be a '\0' at the value returned by strlen(). So an easy way to do this is with another pointer (and use strcpy, not strcat):

Code:

#include <stdio.h>
#include <string.h>

int main(void) {
	int i;
	char s[256]="this", *p = &s[strlen(s)+1];

	for (i = 0; i < 5; i++) {
		strcpy(p,"is");
		p = &p[strlen(p)+1];
	}

// verify
	for (i = 0; i < p-s; i++) {
		printf("%d %c\n", s[i], s[i]);
	}

	return 0;
}

Output:
116 t
104 h
105 i
115 s
0
105 i
115 s
0
105 i
115 s
0
105 i
115 s
0
105 i
115 s
0
105 i
115 s
0

The left column are ascii values. If you don't know what ASCII is, you should:

http://en.wikipedia.org/wiki/ASCII

Of course, '\0' (ascii 0) is not a printable character and you cannot output this whole array with a string function, because it is not a string; it's 6 strings. Note that you will get exactly the same sequence in memory by using an array of strings/2D char array.