通用链表代码C

Question

我已经创建了以下代码:在C中实现链接列表。

为了测试它，我创建了一个标签结构，其中包含一个string和int变量。

在上传到这里之前，代码是很好的注释和测试。

我想听听你对此的看法，我也不确定free和malloc是否运行良好(我使用了DrMemory，它没有出现错误，但是内存是一个“漏”的东西(lol))。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>


/*label */
/*The label is managed by lnode, which contains the address-string(8-bits)
  and the label-name. */
  typedef struct label{
            int   address;             /* The address number.                      */
            char* name;                /* The name of the label.                   */
  }label;

/*Label implementation*/
/*Create label object*/
  label* createLabel(int address, char* name)
  {
      int len;
      label* newlabel;
      if(NULL == name){
         return NULL;
      }
      len = strlen(name)+1;
      newlabel = (label*)malloc(sizeof(label));
      if(NULL == (newlabel->name = (char*)malloc(sizeof(char)*len))){
        return NULL;
      }
    /*copy name to new-label name*/
      strcpy(newlabel->name, name);
    /*set address in newlabel*/
      newlabel->address = address;
      return(newlabel);
  }
/*delete label object*/
  void deleteLabel(void* ob ){
       label *lbl;
       if(NULL == ob){
          return;
       }
       lbl = (label*)ob;
     /*delete the name*/
       free(lbl->name);
     /*delete the Label object*/
       free(lbl);
  }

/*Print Label-objects --> for Testing*/
/*Allocate a string and fill with label data*/
  void printLabel(void* ob){
       label* obl= (label*)ob;
       printf("%s%d,  label: %-10s, ","address: ",obl->address,obl->name);
  }






/*gnode*/
/*generic-node struct to be used in a generic list*/
  struct gnode{
       void *value;        /*pointer to generic-node */
       struct gnode* next; /*pointer to next node    */
  }typedef gnode;


/*createGnode*/
/*create a gnode to be added to a generic-list*/
  gnode* createGnode( void* value, gnode* next){
      gnode* newnode=NULL;
      if(NULL == value){
         return NULL;
      }
      if (NULL == (newnode = (gnode*)malloc(sizeof(gnode)))) {
        return NULL;
      }
    /*add the value*/
      newnode->value = value;
    /*set next value to be NULL --> All added gnode are
      added at the end of the list and become the last node */
      newnode->next = next;
      return(newnode);
  }



/*freeGnode*/
/*free the allocated gnode, using a function to delete the pointed value  */
  void freeGnode(gnode* nodetodelete,  void (*deletefunc)( void*)){
     if(NULL == nodetodelete){
        return;
     }
   /*delete the value, pointed by void* value */
     deletefunc(nodetodelete->value);
   /*free the allocated gnode*/
     free(nodetodelete);
  }


/*insertGnode --> insert gnode to list*/
  int insertGnode(gnode** glist, gnode* newnode)
  {
      gnode* curr; /*pointer to current node in list*/
      if(NULL == newnode){
         return -1; /*no item to insert*/
      }
    /*Empty list*/
      else if(NULL == *glist){
              *glist = newnode;
              return 1;
      }
    /*add newnode in last place in list*/
    /*Get to last node*/
      for( curr = *glist; curr->next != NULL; curr = curr->next);
    /*Add the newnode as last node*/
      curr->next = newnode;
    /*return Success*/
      return 1;
  }


/*deleteGenericList*/
/*Parse each generic-node and delete */
  void deleteGenericList(gnode* glist, void (*deleteValue)(void*))
  {
     gnode* curr=NULL;
     gnode* next;
     if(NULL == glist){
        return;
     }
   /*Delete each generic-node*/
     for(curr = glist; curr != NULL; ){
         next = curr->next;
         deleteValue(curr->value); /*free the value objext     */
         free(curr);               /*free current generic-node */
         curr = next;
     }
   /*Set glist to point at NULL*/
     glist = NULL;
  }/*End deleteGenericList*/


/*writeGlist --> write Gnode to an open-file*/
  void writeGenericList(FILE* fp, gnode* glist, void (*writeValue)(FILE*, void*))
  {
      gnode* curr=NULL; /*curr node in the generic-list*/
    /*check that all arguments are present*/
      if( (NULL == fp)||(NULL==glist)||(NULL==writeValue) ){
           return;
      }
    /*use the writeValue function to write the gnode into the file*/
      for(curr = glist; curr != NULL; curr=curr->next){
          writeValue(fp, curr->value);
      }
  }/*End writeGenericList*/


/*For testing...*/
  void printGlist(gnode* glist, void (*printValue)(void*)){
      gnode *curr;
      if(NULL == glist){
         return;
      }
      for (curr = glist; curr != NULL; curr = curr->next){
           printValue(curr->value);
      }
  }


  void printGlistOLD(gnode* glist, void (*printValue)(void*)){
      gnode *curr;
      if(NULL == glist){
         return;
      }
      printf("%-20s\n", "GenericList: top-To-Bottom");
      for (curr = glist; curr != NULL; curr = curr->next){
           printValue(curr->value);
      }
  }

  int main(int argc, char const *argv[])
  {
    printf("start\n");
    label *label1 = createLabel(100,"hello world");
    label *label2 = createLabel(101,"a");
    label *label3 = createLabel(102,"b");
    label *label4 = createLabel(100,"c");
    label *label5 = createLabel(103,"d");
    label *label6 = createLabel(102,"e");


    gnode* g1 = createGnode(label1,NULL);
    gnode* g2 = createGnode(label2,NULL);
    gnode* g3 = createGnode(label3,NULL);
    gnode* g4 = createGnode(label4,NULL);
    gnode* g6 = createGnode(label6,NULL);
    gnode* g5 = createGnode(label5,g6);

    printf("%d\n",insertGnode(&g1,g2));
    printf("%d\n",insertGnode(&g1,g3));
    printf("%d\n",insertGnode(&g1,g4));
    printf("%d\n",insertGnode(&g1,g5));

    printGlistOLD(g1,printLabel);

    deleteGenericList(g1,deleteLabel);
    return 0;
  }

谢谢!

Answer 1

• 正如我在上一篇评论中提到的，不要在注释中重复代码。我们非常理解strcpy(newlabel->name, name);的目的。
• 正如我在上一次检讨中所说，不要投马洛。
• insertGnode不插入，而是添加到列表中。考虑改名。您似乎并不担心列表中节点的顺序。考虑对新节点进行前缀，如int add_gnode( gnode* * glist，gnode* newnode) { if (newnode == NULL) {rever-1；}newnode>next= *glist；*glist= newnode；返回1；}这种方法有两个好处：
  • 它不是为了找到尾巴而遍历整个列表，而且
  • 这不是特殊情况下的空名单。

• printGlist应该用适当的参数调用writeGenericList。
• 您似乎在努力实现面向对象的方法。考虑让genericList结构以deletefunc、writeValue等为成员。

Answer 2

• 当您不应该使用C语言时，您一直使用void *：newlabel =( label* )malloc(sizeof(标签))；应是: newlabel =malloc(sizeof(标签))；以及void printLabel( void ){ label* obl = (label*)ob；应该是:void(void* ob) {标签* obl = ob；
• 在create_label中有一个潜在的内存泄漏: newlabel = malloc (sizeof(标签))；//不要强制转换malloc if (空== (新标签->name=malloc(sizeof(Char)*len)){返回空；//泄漏先前分配的标签}
• 对于node管理，名称是不一致的:当注释说最后一个时，createGnode插入节点位于第一个位置，而insertGnode将它添加到最后一个位置。
• freeGnode无条件地释放节点及其内容，如果您删除列表中的节点，则=>中的任何链接都可能断开，至少在注释中显示不能从列表中删除节点。
• 在deleteGenericList(gnode* glist, void(*deleteValue)(void*))中，最后一条指令(glist = NULL;)是无操作的，因为它只设置将在下一行超出作用域的函数中的局部值。
• 您应该考虑添加一个函数来从列表中删除节点。