An interesting question about strcat

**meili100** · 07-07-2009

Why the following code prints "Huh?" ?
It seems that 0xFF is never appended to the list by strcat?

Code:

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

const char * const eof = "\0xFF";
char list[2000] = {0};

void append (const char * flower)
{
    strcat (list, flower);
    strcat (list, eof);
}
int main()
{
    const char *next;
    append("Calla Lily");
    append("Daisy");
    append("Tulip");
    next = strchr(list, 0xFF);
    if (!next) printf ("Huh?\n");
}

**laserlight** · 07-07-2009

Change this:

Code:

const char * const eof = "\0xFF";

to:

Code:

const char * const eof = "\xFF";

The former embeds a null character followed by "FF", thus nothing was concatenated.

By the way, if this was supposed to be specifically C rather than the C part of C++, say the word and I shall move the thread. Otherwise, you should #include <cstdio> and <cstring> instead.

**meili100** · 07-07-2009

Thanks lot.
1) Why strchr needs 0xFF with 0 at the beginning? Why not eof = "\0xFF"?
2) Why strchr does not need to escape 0 ?

**laserlight** · 07-07-2009

Originally Posted by meili100

1) Why strchr needs 0xFF with 0 at the beginning? Why not eof = "\0xFF"?

0xFF is an int. "\0xFF" is a string. If you want to use a character constant, then it should be '\xFF'.

Originally Posted by meili100

2) Why strchr does not need to escape 0 ?

It is not about strchr, but the fact that the literal is an int literal.

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