Input redirection Problems

Enter the redirection question-Linux general technology-Linux programming and kernel information. The following is a detailed description. # Include
# Include
# Include
# Include
# Include
# Include

Int main (void )...{
Int filedes;
If (filedes = open ("dd.txt", O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR) <0)
Fprintf (stderr, "% s", "open file error ");
Close (1 );
Dup (filedes );
Close (filedes );
Execlp ("ls", "-l", (char *) 0 );
Return 0;
}

The above is the redirection of the output. I heard that the redirection of the input can only be changed to close (0), but the program prompts "read failed:-: Wrong file descriptor
"
The Code is as follows:
# Include
# Include
# Include
# Include
# Include
# Include

Int main (void )...{
Int filedes;
If (filedes = open ("dd.txt", O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR) <0)
Fprintf (stderr, "% s", "open file error ");
Close (0 );
Dup (filedes );
Close (filedes );
Execlp ("sort", "sort", (char *) 0 );
Return 0;
}