Question

我正在创建一个变量树，但是看似在insert或print_wevr函数中却出现了一个错误。

运行程序时，出现无限循环。

我该怎么办？

/*5 - VarTrees*/

/*var_trees.c*/

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

/*Defining the struture of variable tree.
 * The nodes has tree fields: 
      info: an generic information
      first: the first child-node
      next: the next sibling-node
 */

struct var_tree{
    void* info;
    Var_Tree* first;
    Var_Tree* next;
};

/*Create the tree*/
Var_Tree* create(void* info)
{
    Var_Tree* t = (Var_Tree*) malloc(sizeof(Var_Tree));
    t->info = info;
    t->first = NULL;
    t->next = NULL;
    return t;
}

/*Insert a node*/
void insert(Var_Tree* t,Var_Tree* st)
{
    st->next = t->first;
    t->first = st;
}

/*go_through the tree*/
void go(Var_Tree* t, void (*cb)(void*))
{
    Var_Tree* p;
    cb(t->info);
    for(p = t->first; p != NULL; p = p->next)
        go(t,cb);
    printf(">");
}

/*Remove a node*/
//void remov(Var_Tree* t, void* info);


/*5 - VarTrees*/

/*main.c*/

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

Var_Tree* create_int(int info)
{
    return create(&info);
}

void print_int(void* info)
{
    int* t = (int*) info;
    printf("<%d",*t);
}

int main(void)
{
    Var_Tree* a = create_int(4);
    Var_Tree* b = create_int(3);
    Var_Tree* c = create_int(23);
    Var_Tree* d = create_int(1);
    Var_Tree* e = create_int(2);

    insert(a,b);
    go(a,print_tree);
}

函数create_int是用于创建字段信息为int的节点的函数。

print_int是一个回调函数，可打印整数（“ <”为树创建一种文本符号）。

Answer 1

在go函数中，您正在进行递归调用，而无需更改最终导致无限递归的参数。

  void go(Var_Tree* t, void (*cb)(void*))
{
    Var_Tree* p;
    cb(t->info);
    for(p = t->first; p != NULL; p = p->next)
        go(t,cb); //<-----here you are calling the same 
    function with the same parameter that leads to an infinite loop
    printf(">");
}

您应该传递p的值代替t。

void go(Var_Tree* t, void (*cb)(void*))
{
    Var_Tree* p;
    cb(t->info);
    for(p = t->first; p != NULL; p = p->next)
        go(p,cb);  //<----change t to p
    printf(">");
}

通用变量树错误无限循环

1 个答案: