Rdt3.0 sender and receiver Program (C implementation)

This is something I used in my network theory experiment. I shared it with everyone. ^_^ (it seems that some of them are not right. If they are useful, please pay attention to it)

Sender:

# Include <stdio. h>
Void sendata0 ();
Void start ();
Void waitack ();
Void retrans1 ();
Void retrans0 ();
Void sendata1 ();
Void main ()
{
Int;
Int B;
Int C;
Int D;
Start (); // start the program
Return;
}
Void start (){
Int;
While (! = 1 &! = 2)
{
Printf ("******************************/N "); // initial Page
Printf ("Welcome to RDT 3.0 sender demo/N ");
Printf ("1: send data 2: Exit demo/N ");
Printf ("Enter your choice :");
Scanf ("% d", & );
Printf ("************************************* * *******************/N ");
}
If (A = 1)
Sendata0 (); // send data with a serial number of 0
If (A = 2)
Exit (0); // exit the program
}

//************************************** *****************************
Void sendata0 () // send a packet whose serial number is 0
{
Int B;
While (B! = 1 & B! = 2)
{
Printf ("Send a packet with the serial number 0 now. Are you sure you want? /N ");
Printf ("1: OK 2: Exit ");
Scanf ("% d", & B );
Printf ("************************************* * *******************/N ");
}
If (B = 1)
Waitack (); // wait for the ACK message to be received
If (B = 2)
Start (); // return the Start Program

}

Void waitack (){
Int C;
While (C! = 1 & C! = 2 & C! = 3 & C! = 4 ){
Printf ("packets with serial number 0 have been sent !! The timer has been started:-)/n ");
Printf ("select event/N ");
Printf ("1: ack0 received 2: ack1 received 3: ACK 4 received error: Timeout !! /N ");

Scanf ("% d", & C );
Printf ("************************************* * *******************/N ");
}
If (C = 2 | C = 3 | C = 4)
Retrans0 (); // resend the data packet with the serial number 0;
If (C = 1)
Sendata1 (); // send a data packet with the serial number of 1;

}

Void retrans0 (){
Printf ("packets with serial numbers 0 will be ressent/N ");
Waitack (); // wait for ACK
}

Void sendata1 (){
Int D;
Printf ("the packet whose serial number is to be sent now/N ");
While (D! = 1 & D! = 2 & D! = 3 & D! = 4)
{
Printf ("packets with serial number 1 have been sent and are waiting for a response/N ");
Printf ("1: ack1 received 2: ack0 received 3: timeout! 4: receive error message/N ");
Printf ("select event ");
Scanf ("% d", & D );
Printf ("************************************* * *******************/N ");
}
If (D = 2 | D = 3 | D = 4)
Retrans1 (); // re-transmits the first packet
If (D = 1)
Sendata0 (); // return to the data packet No. 0 to be sent

}
Void retrans1 (){
Printf ("packets whose serial number is to be ressent/N ");
Sendata1 (); // resend the data packet No. 1
}

Aggreger:

# Include <stdio. h>
Void start ();
Void recv0 ();
Void recall0 ();
Void sendack1 ();
Void recall1 ();
Void sendack0 ();
Void recv1 ();

Void main (){
Int;
Int B;
Int C;
Int D;
Int E;
Start (); // Start Screen
Return;
}
Void start (){
Int;
While (! = 1 &! = 2 ){
Printf ("*******************************/N ");
Printf ("welcome to the RDT 3.0 receiver demo !!! /N ");
Printf ("1: Enter the received DEMO 2: Exit/N ");
Printf ("Enter your choice ");
Scanf ("% d", & );
Printf ("*********************************/N" );
}
If (A = 1)
Recv0 (); // enters the status of receiving packet 0
If (A = 2)
Exit (0); // exit the program

}
Void recv0 (){
Int B;
While (B! = 1 & B! = 2 & B! = 3 ){
Printf ("the sender has sent a packet with the serial number 0/N ");
Printf ("select event:/N ");
Printf ("1: receive the correct data 2: receive the wrong data 3: timeout/N ");
Scanf ("% d", & B );
Printf ("*******************************/N ");
}
If (B = 1)
Sendack1 (); // connect to the received data packet for confirmation
If (B = 2 | B = 3)
Recall0 (); // send the message so that the sender retransmits it.
}

Void sendack1 (){
Int C;
While (C! = 1 & C! = 2 ){
Printf ("packets with serial number 0 have been correctly received !! /N ");
Printf ("select an event! /N ");
Printf ("1: Send ack0 2: Quit/N ");
Scanf ("% d", & C );
Printf ("*****************************/N ");
}
If (C = 1)
Recv1 (); // changes to the status of waiting for receiving data packets whose serial number is 1
If (C = 2)
Start (); // return the start status
}
Void recall0 (){
Printf ("ack1 needs to be sent to the sender !! /N ");
Printf ("ack1 has been sent !!! /N ");
Printf ("****************************/N ");
Recv0 ();
}

Void recv1 (){
Int D;
While (D! = 1 & D! = 2 & D! = 3 ){
Printf ("the sender has sent packet 1 !! /N ");
Printf ("select event/N ");
Printf ("1: receive the correct data 2: receive the wrong data 3: timeout/N ");
Scanf ("% d", & D );
Printf ("*************************/N ");
}
If (D = 1)
Sendack0 ();
If (D = 2 | D = 3)
Recall1 ();
}

Void sendack0 (){
Int E;
While (E! = 1 & E! = 2 ){
Printf ("packets with serial number 1 have been received !! /N ");
Printf ("select event/N ");
Printf ("1: Send ack1 2: Quit ");
Scanf ("% d", & E );
Printf ("*************************/N ");
}
If (E = 1)
Recv0 ();
If (E = 2)
Start ();
}

Void recall1 (){
Printf ("ack0 needs to be sent for sender to re-transmit !! /N ");
Printf ("ack0 has been sent !!! /N ");
Printf ("************************/N ");
Recv1 ();
}
The Code comes from reference materials on hand ..