Trie tree query based on C/S architecture

1. simulate a score query system. The user enters the name and returns the corresponding score. The entire Query Process is run on the server and the Trie tree is used to accelerate the query. Code 2 server:

#include <stdio.h>  #include <unistd.h>  #include <stdlib.h>  #include <sys/types.h>  #include <sys/socket.h>  #include <signal.h>  #include <netinet/in.h>  #include <ctype.h>    #define N 8  typedef const char * keyType;  typedef unsigned int valType;  /*  * to define a Person structure and initialize  * */  typedef struct Person {      keyType name;      valType score;  }Person;  Person person[N] = {{"LiTao", 89}, {"ZhangQiang", 77},  {"ChengTianXiong", 88}, {"ZhangWei", 90},      {"SongTao", 100}, {"LiMin", 88}, {"SongZuDe", 88}, {"ChengFei", 66}};  /*  * to define Trie node structure  * */  enum NodeType {UNCOMPLETED, COMPLETED};  typedef struct TrieNode {      enum NodeType type;      char ch;      valType val;      struct TrieNode *child[26];  }TrieNode;  TrieNode *root;  // the root of trie   /*  * to define some functions for Trie   * */  TrieNode * newTrieNode(char ch) {      TrieNode *p =(TrieNode *)malloc(sizeof(TrieNode));      if(!p) {      perror("Memory error!\n");      exit(1);      }      p->type = UNCOMPLETED;      p->ch = ch;  //  memset(p->child, NULL, sizeof(p->child)); // there are some warnings if using memset       int i;      for(i = 0;i < 26;i++) p->child[i] = NULL;        return p;  }  int index(char ch) {      if(isupper(ch)) ch = tolower(ch);      return ch - 'a';  }  void createTrieroot() {      root = newTrieNode('@');  }  void insertNode(keyType key, valType val) {      TrieNode *ptr = root;      int pos;      int i;      for(i = 0;key[i];i++) {      pos = index(key[i]);      if(ptr->child[pos] == NULL) {          ptr->child[pos] = newTrieNode(key[i]);      }      ptr = ptr->child[pos];      }      ptr->type = COMPLETED;      ptr->val = val;  }  /*  * to find the val in terms of key   * return -1 if fail to find   * */  int find(keyType key) {      TrieNode *ptr = root;      int pos;      int i;      for(i = 0;key[i];i++) {      pos = index(key[i]);      if(ptr->child[pos] == NULL) break;      ptr = ptr->child[pos];      }      if(!key[i] && ptr->type == COMPLETED) return ptr->val;      else return -1;  }  void createTrie() {      if(root) return;      createTrieroot();      int i;      keyType key;      valType val;      for(i = 0;i < N;i++) {      key = person[i].name;      val = person[i].score;      if(find(key) == -1) {          insertNode(key, val);      }      }  }  int main() {      createTrie();      /*      * to test some cases      * */  //  char name[20];  //  while(1) {  //    gets(name);  //        int val = find(name);  //        printf("%d\n", val);  //}      /*      * the socket fd is same the file descriptor      * */      int server_sockfd = -1;      int client_sockfd = -1;      int client_len = 0;      /*      * to define socket address      * */      struct sockaddr_in server_addr;      struct sockaddr_in client_addr;      /*      * to create a socket       * a socket contains domain, type and protocal      * */      server_sockfd = socket(AF_INET, SOCK_STREAM, 0);  //  bzero(&server_addr, sizeof(server_addr));  // to clear the server_addr      /*      * to initialize the socket address       * */      server_addr.sin_family = AF_INET;      server_addr.sin_addr.s_addr = htonl(INADDR_ANY);      /*      * pay attention      * the port should be same with the port from client       * */      server_addr.sin_port = htons(9736);      /*      * to bind the sockect and its address       * */      bind(server_sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));      /*      * to listen the port       * */      listen(server_sockfd, 5);      /*      * to ignore child processes which stop       * */     signal(SIGCHLD, SIG_IGN);            while(1) {      keyType key;          valType val = -1;        client_len = sizeof(client_addr);      printf("server is waiting...\n");      /*      * to accept a connect from a client socket       * */      client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_addr, &client_len);          /*      * let the child process to deal with       * */      if(fork() == 0) {          /*          * read data from socket           * */          char name[20];          read(client_sockfd, &name, sizeof(name));          int  score = find(name);     // to search in the trie           /*          * write the data to socket           * */          write(client_sockfd, &score, sizeof(score));          close(client_sockfd);          exit(0);      }      else {          close(client_sockfd);      }      }      close(server_sockfd);      return 0;  }  

 

Client:

#include <stdio.h>  #include <unistd.h>  #include <stdlib.h>  #include <sys/types.h>  #include <sys/socket.h>  #include <signal.h>  #include <netinet/in.h>  #include <arpa/inet.h>    int main() {      /*      * the socket fd is same the file descriptor      * */      int sockfd = -1;      int len = 0;      /*      * to define socket address      * */      struct sockaddr_in address;      int result;        char name[20];      unsigned int score;        int i;      for(i = 0;i < 10;i++) {      /*      * to create a socket       * a socket contains domain, type and protocal      * */      sockfd = socket(AF_INET, SOCK_STREAM, 0);      /*      * to initialize the socket address       * */      address.sin_family = AF_INET;      address.sin_addr.s_addr = inet_addr("127.0.0.1");      address.sin_port = htons(9736);      len = sizeof(address);      /*      * to connect the server       * */      result = connect(sockfd, (struct sockaddr *)&address, len);      if(result == -1) {      perror("ops:client!\n");      exit(1);      }        printf("input a name:");      gets(name);      write(sockfd, &name, sizeof(name));      read(sockfd, &score, sizeof(score));      printf("score from server = %d\n", score);        close(sockfd);      }      exit(0);        return 0;  }