[英]Binary Search Tree insertion doesn't work
I am following a book ,Problem Solving & Program Design in C, to learn C. In this book, they gave all necessary parts to build a binary search tree.... But, My implementation didn't work. 我正在学习《用C解决问题和程序设计》一书,以学习C。在本书中,他们给出了构建二进制搜索树的所有必要部分。...但是,我的实现没有用。 Here is insertion part;
这是插入部分;
void
add_to_t(tree_node_t *oldTreep, // input/output - binary search tree
tree_element_t ele) // input - element to add
{
oldTreep = tree_insert(oldTreep, ele);
}
tree_node_t * tree_insert(tree_node_t *oldTreep, tree_element_t ele)
{
if(oldTreep == NULL){
oldTreep = TYPED_ALLOC(tree_node_t);
strcpy(oldTreep->element.name, ele.name);
strcpy(oldTreep->element.sName, ele.sName);
oldTreep->element.seatClass = ele.seatClass;
oldTreep->leftp = NULL;
oldTreep->rightp = NULL;
}
else if (strcmp(oldTreep->element.name, ele.name)==0){
/* duplicate key - no insertion */
}
else if (strcmp(oldTreep->element.name, ele.name)>0){
oldTreep->rightp = tree_insert(oldTreep->rightp, ele);
}
else
{
oldTreep->leftp = tree_insert(oldTreep->leftp, ele);
}
return(oldTreep);
}
My scan_passenger funvtion(I am passing ele from result of this function call); 我的scan_passenger函数(我正在从此函数调用的结果传递ele);
void scan_passenger(tree_element_t *pass)
{
char passName[10], passSname[10];
int classNum;
printf("\nEnter the Name of passenger to add the binary search tree> ");
scanf("%s", passName);
printf("Enter the Surname of passenger to add the binary search tree> ");
scanf("%s", passSname);
printf("Enter the class number of passenger to add the binary search tree> ");
scanf("%d", &classNum);
strcpy(pass->name, passName);
strcpy(pass->sName, passSname);
pass->seatClass = classNum;
}
And my typdefs and headers if needs; 还有我的typdef和标头(如果需要);
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#define TYPED_ALLOC(type) (type *)malloc(sizeof (type))
typedef struct tree_element_s {
char name[10];
char sName[10];
int seatClass;
}tree_element_t;
typedef struct tree_node_s {
tree_element_t element;
struct tree_node_s *leftp, *rightp;
}tree_node_t;
My problem is that it doesn't create a root of binary search tree. 我的问题是它不会创建二进制搜索树的根。 When I try to add a new element to heap, it seems, it creates a new node.
当我尝试向堆中添加新元素时,它似乎会创建一个新节点。 When I traced my code, it seems every instance of this functions returns NULL.
当我跟踪代码时,似乎此函数的每个实例都返回NULL。 I am trying to say every time when I call tree_insert, it goes first if statement(Thinks root is NULL)... Sorry for my bad English.
我想说的是每次我调用tree_insert时,如果语句(认为root为NULL)首先出现……对不起,我的英语不好。 And I may made some mistake when talking about coding terminology(it may because, I returned to study C from that book after absence of 1 year.So I may mixed them) Thanks in advance.
在谈论编码术语时,我可能会犯一些错误(可能是因为,缺席1年后,我从那本书中重新学习了C语言,所以我可能会把它们混在一起)。
In add_to_t, you update oldTreep, but since it is a local variable, the new value gets lost as soon as you leave the function. 在add_to_t中,您更新了oldTreep,但由于它是一个局部变量,所以一旦离开该函数,新值就会丢失。
You could, eg, return the new value of oldTreep to the caller, which updates his oldTreep with the return value 例如,您可以将oldTreep的新值返回给调用者,调用者将使用返回值更新其 oldTreep
tree_node_t
add_to_t(tree_node_t *oldTreep, // input/output - binary search tree
tree_element_t ele) // input - element to add
{
return tree_insert(oldTreep, ele);
}
...
myRootOfTheTree = add_to_t (myRootOfTheTree, element);
Another solution is to always have one dummy element in the tree. 另一种解决方案是在树中始终有一个虚拟元素。
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