Programming

        #include <stdlib.h>
        #include <stdio.h>
        #include <unistd.h>
        #include <sys/types.h>
        #include <ctype.h>
        #include <sys/socket.h>
        #include <string.h>
        #include <netinet/in.h>
        #define MAXLENGTH 80
        #define SERVERPORT 1313


        void minuscolatore (int in,int out){
            char inputline[MAXLENGTH];
            int len,i;
            while((len=recv(in,inputline,MAXLENGTH,0))>0){
                for(i=0;i<len;i++){
                    inputline[i]=tolower(inputline[i]);
                }
                if (strcmp(inputline,"fine")==0){
                    break;
                }
                send(out,inputline,len,0);
            }
        }
        void maiuscolatore(int in,int out){
            char inputline[MAXLENGTH];
            int len,i;
            while((len=recv(in,inputline,MAXLENGTH,0))>0){
                for(i=0;i<len;i++){
                    inputline[i]=toupper(inputline[i]);
                }
                if (strcmp(inputline,"FINE")==0){
                    break;
                }
                send(out,inputline,len,0);
            }
        }
        int main(){
            int sock,client_len,fd;
            char c;
            struct sockaddr_in client, server = {AF_INET,htons(SERVERPORT),INADDR_ANY};
            if((sock=socket(AF_INET,SOCK_STREAM,0))==-1){
                perror("Socket fallita");
                exit(1);
            }
            if(bind(sock,(struct sockaddr *)&server,sizeof server)==-1){
                perror("Bind fallita");
                exit(2);
            }
            listen(sock,5);
            while(1){
                client_len=sizeof(client);
                if((fd=accept(sock,(struct sockaddr *)&client,&client_len))<0){
                    perror("accept fallita");
                    exit(3);
                }
                if (recv(sock,&c,1,0)==-1){
                    perror("recv server fallita");
                    exit(4);
                }
                if (c=='+'){
                switch(fork()){
                    case -1:
                        perror("Fork fallita");
                        exit(4);
                    case 0:
                        printf("Aperta connessione\n");
                        send(fd,"Benvenuto al maiuscolatore, minuscolatore\n",27,0);
                        maiuscolatore(fd,fd);
                        printf("Chiusa connessione\n");
                }
            }
                else if (c=='-'){
                switch(fork()){
                    case -1:
                        perror("Fork fallita");
                        exit(4);
                    case 0:
                        printf("Aperta connessione\n");
                        send(fd,"Benvenuto al maiuscolatore, minuscolatore\n",27,0);
                        minuscolatore(fd,fd);
                        printf("Chiusa connessione\n");
                }   
                }
            }
            close(fd);
        }