A simple TCP echo server and client

This is simple example of tcp server and client. Here client write something on server socket and server write same message back to client.

Few observation:
- What happen if client tries to write 40 byte of date on server socket and reads   40 byte while server writes 20 and reads 20.
- fork process share its parent file descriptor. 
- In the forked server socket try to print on terminal some message without use of '\n' it will not print
 e.g.
 void str_echo(int sockfd)
    {
      char buff[20];
      ssize_t n;
      while(1)
          {
           if((n=read(sockfd,buff,20))>=0)
              write(sockfd,buff,20);
           else
              write(sockfd,"blank",20);
           //else
             printf("%s\n",buff);        // if i replace it with printf("%s",buff) then it wont work
             // write(sockfd,buff,20);
              //return;
           //else
             // writen(sockfd,buff,n);
           }
     }
echo server:
#include<stdio.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<string.h>
#include"str_echo.c"

    

int main()
  {
   int sockfd,connfd,childpid,clilen;
   struct sockaddr_in cliaddr,servaddr;

   sockfd=socket(AF_INET,SOCK_STREAM,0);
 
   bzero(&servaddr,sizeof(servaddr));
   servaddr.sin_family=AF_INET;
   servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
   servaddr.sin_port=htons(6060);
   bind(sockfd,(struct sockaddr*) &servaddr,sizeof(servaddr));
   
   listen(sockfd,5);

   while(1)
     {
      clilen=sizeof(cliaddr);
      connfd=accept(sockfd,(struct sockaddr*)&cliaddr,&clilen);
      printf("connection accepted\n");
       if((childpid=fork())==0)
          {
            close(sockfd);
            printf("child process\n");
            str_echo(connfd);
           // str_echo(connfd);
            exit(0);
          }
     printf("connection established\n");
     close(connfd);
     }
}

echo client:
#include<stdio.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<string.h>
#include"str_cli.c"
int main()
   {
   int sockfd;
   char buff[20];
    ssize_t n;
   struct sockaddr_in servaddr;
    printf("before socket");
   sockfd=socket(AF_INET,SOCK_STREAM,0);
   printf("socket created");
   bzero(&servaddr,sizeof(servaddr));
   servaddr.sin_family=AF_INET;
   inet_pton(AF_INET,"127.0.0.1",&servaddr.sin_addr);
   servaddr.sin_port=htons(6060);
   //bind(sockfd,(struct sockaddr*)&cliaddr,sizeof(cliaddr));
   printf("before connection");
   if(connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr))==0)
      {
         printf("inside loop");
         str_cli(sockfd); 
         /*write(sockfd,"sdfhsdkf",20);
          printf("request send");
         n=read(sockfd,buff,20);
         printf("%s",buff);*/
       }
   printf("after connection");
   close(sockfd);
   }