Question

所以，这是我教授提供的示例程序。它的功能是搜索树的链表并返回天气的结果，或者找不到用户输入的树。但是，无论我输入什么，它总是返回false。它有什么问题？

#include <stdio.h>
#include <string.h>
#define NL 20

typedef struct tree 
{
    char tree_name [NL];
    struct tree* next;
}tree;

int 
checktree (tree *p, char name[])
{
   int found = 0;
   while (p != NULL)
   {
       if (strcmp(p -> tree_name, name) == 0)
          found = 1;
       p = p -> next;
   }
   return (found);
}


int
main (void)
{
    /* declaring variables to hold tree nodes */
    tree tree1, tree2, tree3, tree4;

    /* declaring the starting and traveling pointers */
    tree *p, *start;

    char treename[NL];

    /* putting tree names into each node */
    strcpy (tree1.tree_name, "Maple");
    strcpy (tree2.tree_name, "Fir");
    strcpy (tree3.tree_name, "Pine");
    strcpy (tree4.tree_name, "Oak");

    /* setting the start of the list at tree1 */
    start = &tree1;

    /* linking the other trees together */
    tree1.next = &tree2;
    tree2.next = &tree3;
    tree3.next = &tree4;

    /* sets tree4 as the last node of the list  */
    tree4.next = NULL;

    /* checking if a tree is in the list */
    printf ("Enter tree name to search: ");
    fgets (treename,sizeof(treename),stdin);

    if (checktree(start, treename))
       printf ("%s was found in our list of trees.\n", treename);
    else
       printf ("%s was not found in our list of trees.\n", treename);
    return (0);
}

Answer 1

fgets读取一行也包含换行符。在调用checktree之前添加代码以将其删除。

fgets (treename,sizeof(treename),stdin);
int len = strlen(treename);
if ( treename[len-1] == '\n' )
{
   treename[len-1] = '\0';
}

if (checktree(start, treename)) { ... }

涉及链接列表和结构的示例程序不起作用

1 个答案: