[c-prog] string question

[int21h_d]

can someone explain why the "thequickbrown..." doesnt concatenates after
the "hello world", that is, "hello worldthequickbrownfox...." ???


thanks in advance!!!


int main(int argc, char *argv[])
{

    char buff[80];
    sprintf(buff, "hello world");
    printf("%s\n", buff);
    buff[strlen(buff)]=strcat(buff,"thequickbrownfoxjumpsoverthelazydog");
    printf("%s\n", buff);
    getch();
    return 0;
}