Socket non-blocking setting error

Socket non-blocking setting error-Linux general technology-Linux programming and kernel information. The following is a detailed description. Some code
Pclient-> socket = socket (AF_INET, SOCK_STREAM, 0 );
Pclient-> _ addr. sin_family = AF_INET;
Pclient-> _ addr. sin_port = htons (pclient-> remote_port );
Pclient-> _ addr. sin_addr = * (struct in_addr *) he-> h_addr );
If (pclient-> socket =-1 ){
Return-1;
}
Flags = fcntl (pclient-> socket, F_GETFL, 0); client_recv (pclient, & lpbuf, 0) <= prp_enc_disable
Fcntl (pclient-> socket, F_SETFL, flags | O_NONBLOCK );

After the last two lines of comments are added, the program runs and sends a message to the server. messages can be received normally. an error is reported when the program stops running without commenting.
Error
* ** Glibc detected **./main: free () csi enable mclk
: Invalid pointer: 0xbe942558 ** prp_enc_disable
*
Aborted

How should we set it to non-blocking mode?