Question

我想在列表的末尾插入结构，我无法编译代码。以下是我对insert（）函数的一些伪代码。他们的其余代码应该保持不变。

 (check it succeeded)
 set the data for the new person
 if the current list is empty (i.e. NULL)
   do the same as insert_start i.e.
   set the new person's "next" link to point to the current list (i.e. NULL)
   return the (start of the) new list i.e. a pointer to the new person
 otherwise
   use a loop to find the last item in the list
     (i.e. the one which has a "next" link of NULL)
   set the "next" link of this item to point to the new person
     so the new person becomes the last item in the list
     (i.e. the new person should have a "next" link of NULL)
       return the (start of the) list

编译错误：

error: 'true' undeclared (first use in this function)
insert_end.c:47:13: note: each undeclared identifier is reported only once for each function it    appears in
insert_end.c:57:3: warning: 'return' with a value, in function returning void
make: *** [insert_end] Error 1




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


/* these arrays are just used to give the parameters to 'insert',
 to create the 'people' array */
char names[][10]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim",
      "Harriet"};
int ages[7]= {22, 24, 106, 6, 18, 32, 24};


/* declare your struct for a person here */
typedef struct Record{
  char *name;
  int age;
  struct Record *next;
}  Record;

//set the head pointer at the start of the list
Record *headptr = NULL;

static void insert (Record *p, char *s, int n) {

  /* allocate heap space for a record */
  Record *ptr =(Record*) malloc(sizeof(Record));

  if(ptr == NULL){  
    abort();
    printf("memory allocation fail"); 
    exit(1);  
  }else{
    printf("memory allocation to person  - %s - \n", s);      
  }

  ptr->name=s;
  ptr->age=n;
  ptr->next = NULL;

  if(p->next==NULL)
  {
     p->next= ptr;

  }else{
      Record *current = p;
      while(true){

    if(current->next ==NULL)
{
  current->next = ptr;
  break;
}
current= current->next;
  }
  }
  return 0;

}  

int main(int argc, char **argv) {

      /* declare the people array here */
  Record *p;
  headptr = NULL;

   //insert the members and age into the unusage array. 
  for (int i=0; i < 7; i++) {
    insert (p, names[i], ages[i]);
    /* do not dereference the pointer */
  }

  /* print out a line before printing the names and ages */
  printf("\n");

  //set the pointer at the start of the list 
  p = headptr;

  /* print the people array here*/
  for (int i=0; i < 7; i++, p = p->next) {
    printf("The name is: %s, the age is:%i\n", p->name, p->age);
  }


  /* This is the third loop for call free to release the memory allocated by malloc */
  /* the free()function deallocate the space pointed by ptr. */
  for(int i=0; i<7;i++){
    free(p);
  }


}

Answer 1

'true'和'false'需要在c中定义。否则使用1和0代替。返回0将不起作用，因为该函数被定义为void。要么从声明中删除'void，要么使用'return;'

在C的列表末尾添加新结构

1 个答案: