Send chars with UDP

I'm trying to send text with UDP, by sending every character separately, but something seems to be wrong. This is the client:

while(strcmp(sir,"0")!=0)
{
     printf("Text number %d:", i);
     i++;
     scanf("%s",sir);
     printf("\n");
     sirLen=strlen(sir);
     for(j=0;j<sirLen;j++)
     {     c=sir[j];
          printf("%c",c);
          sendto(sock, &c, sizeof(char), 0, (struct sockaddr *)&ServAddr, sizeof(ServAddr));
     }
}

raspunsLen=recvfrom(sock, raspuns, SIRMAX, 0,(struct sockaddr *) &fromAddr, &fromSize);
raspuns[raspunsLen] = '\0';
printf("%s",raspuns);

And this would be the server:

for (;;) 
{
    cliAddrLen = sizeof(ClntAddr); 
    while(sir != '0')
    { 
      recvfrom(soc开发者_如何学Gok, &sir, sizeof(char), 0,(struct sockaddr *) &ClntAddr, &cliAddrLen);
      raspuns[i]=sir;
      printf("%c",sir);
    }
    raspunsMsgSize=strlen(raspuns); 
    sendto(sock, raspuns, raspunsMsgSize, 0, (struct sockaddr *) &ClntAddr,             sizeof(ClntAddr));
}

It works when I send whole pieces of text but this way the server doesn't seem to be receiving anything. Hope someone can help. Thank you.

I suspect:

while(sir != '0')

should be:

while(sir != 0)

or possibly:

while( * sir != 0 )

But really, you haven't posted enough code to be sure.