c - 结构数组奇怪的输出？

Question

任何人都可以告诉我为什么结构数组不能正确打印吗？

我认为这与我分配给我不确定的结构的内存有关!

使用 mac osx mountain lion xcode 4 gcc

感谢您的帮助，完全陷入困境!(请耐心等待，我只是一名学生!)

#include <stdio.h>
#include <limits.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>



typedef struct{
char* one;  
char* two;
 } Node;

 Node *nodes;
 int count = 0;


 //-----------------------------------------------------------------------
 void add(char *one,char*two){

 char x[40];
 char y[40];

 printf("reached..\n");

 strcpy(x,one);
 strcpy(y,two);


 printf("--> X: %s\n",x); 
 printf("--> Y: %s\n",y); 

 Node newNode;
 newNode.one = x;
 newNode.two = y;
 nodes[count]= newNode;

 count++;
 }
 //-----------------------------------------------------------------------

 //-----------------------------------------------------------------------
void print(){

 int x;
 for (x = 0; x < 10; x++)
 {
   printf("%d : (%s, %s) \n",x,nodes[x].one, nodes[x].two);
 }

 }

 //-----------------------------------------------------------------------

 //-----------------------------------------------------------------------
 void check(char **arg)
 {

if(strcmp(*arg, "Add") == 0)
{

add(arg[1],arg[2]);

}else if(strcmp(*arg,"print") == 0)
{

 print();
}else{
    printf("Error syntax Enter either: \n Add [item1][item2]\n OR \n print\n");
}

 }
 //-----------------------------------------------------------------------
 void readandParseInput(char *line,char **arg)
 {  

  if (fgets (line, 512, stdin)!= NULL) {  


  char * pch;
  pch = strtok (line," \n\t");
  int count = 0;
  arg[0] = pch;

  while (pch != NULL)
   {
   count++;
   pch = strtok (NULL, " \n\t"); 
   arg[count] =pch;
   }


}else{
printf("\n");
exit(0);
  }

 }

 //-----------------------------------------------------------------------

 int main() 
{


 int size = 100;
 nodes = calloc(size, sizeof(Node));

 int i;
 for(i = 0;i <100; i++){

 printf("%s , %s \n",nodes[i].one,nodes[i].two );
 // nodes[i].one = ".";
 // nodes[i].two = ".";
 }


 char  line[512];             /* the input line                 */
 char  *arg[50];              /* the command line argument      */

while (1) 
{ 
  readandParseInput(line,arg);
  if(arg[0] != NULL){
    check(arg);
    }

 }

return(0);
}

Answer 1

您将保留指向以下自动变量的指针:

 char x[40];
 char y[40];

当add()返回时，这些会超出范围，留下悬空指针。

您必须将 Node::one 和 Node::two 转换为数组，或者在堆上为它们分配内存。