c++ - Unable to send pdf through binary with UDP -

i having trouble sending pdf file client server reading file in binary. using udp transfer , when send text file client server receive file without errors when send pdf error opening file. heres have both sender , receiver:

sender:

file = fopen(file_name_char, "rb"); //read in binary here  int size_count = (file_size / (buffer_size - 2)) + 1; //amount of times loop              (int = 0; < size_count; i++)             {                 memset(szbuffer, 0, buffer_size);                 fread(szbuffer, sizeof(char), buffer_size - 2, file); //read buffersize -2 (reserve spot bit , \0)                  strcpy(szbuffer, concat(current_bit, szbuffer));                  send_with_select(s, szbuffer, (struct sockaddr*)&sa1, (struct sockaddr*)&sa1, sa1_length, current_bit, "file contents", 0); //send file contents                  file_size = file_size - buffer_size + 2; //decrease size                  client_bit = change_bit(client_bit);                 *current_bit = bit_string(client_bit);                 //change bit             }             fclose(file); 

for udp transfer prepending each buffer sequence number simulate stop n wait protocol

receiver:

int size_count = (file_size / (buffer_size - 2)) + 1; //amount of times loop              (int = 0; < size_count; i++)             {                 file = fopen(file_name, "ab");                  //open file writing                  memset(szbuffer, 0, buffer_size);                 receive_packet_transfer(s, szbuffer, (struct sockaddr*)&sa_in, (struct sockaddr*)&sa_in, sa_length, current_bit, content, "file contents", client_bit); //receive file contents                  client_bit = change_bit(client_bit);                 *current_bit = bit_string(client_bit);                 //change bit                  if (file_size <= buffer_size)                     fwrite(content, sizeof(char), file_size, file);                 else                     fwrite(content, sizeof(char), buffer_size - 2, file); //write file                  file_size = file_size - buffer_size + 2; //decrease size                 fclose(file);             } 

i have implemented send_with_select() , receive_packet_transfer() using sendto() recvfrom() methods. same thing wait ack or timeout (using select).

strcpy(szbuffer, concat(current_bit, szbuffer));

string manipulation functions strcpy, strlen etc work textual data cannot contain \0 because consider \0 end of string. pdf binary , can contain \0. strcpy copy data first \0.

apart that, using udp transfer files bad idea unless make sure can deal lost packets, duplicate packets , packet reordering. better use tcp cares this.