【发布时间】：2012-08-31 02:06:37
【问题描述】：
我正在尝试搜索哈希表，但遇到了一些问题。我的代码可以编译，但它有问题。我不太确定是什么。当我在命令提示符下运行它并将文件传递给程序时。我在搜索时遇到了一些问题
0 不真诚
struct htablerec {
char **key;
int *frequencies;
int num_keys;
int capacity;
};
static unsigned int htable_word_to_int(char *word) {
unsigned int result = 0;
while (*word != '\0') {
result = (*word++ + 31 * result);
}
return result;
}
int htable_insert(htable h, char *str) {
int i;
/*convert string to integer*/
unsigned int index = htable_word_to_int(str);
/*calculate index to insert into hash table*/
int remainder = index%h->capacity;
/*once calculated position in the hash table, 3 possibilities occur*/
/*no string in this positon, copy string to that position,
increment number of keys, return 1*/
if (h->key[remainder] == NULL) {
char *key = emalloc(strlen(str) + 1);
strcpy(key, str);
h->key[remainder] = key;
h->frequencies[remainder] = 1;
h->num_keys++;
return 1;
}
/*the exact same string is at the position,
increment frequency at that position,
return frequency*/
if (strcmp(str, h->key[remainder]) == 0) {
h->frequencies[remainder]++;
return h->frequencies[remainder];
}/*a string is at that position, but it isnt the rightone,
keep moving along the array until you find either an open
space or the string you are looking for*/
if (h->key[remainder] != NULL && strcmp(str, h->key[remainder]) != 0) {
/*you may need to wrap back around to the beginning of the table,
so each time you add,to the position you should also mod
by the table capacity.*/
for (i = 0; i < h->capacity; i++) {
/*no string in this positon, copy string to that position,
increment number of keys*/
if (h->key[remainder] == NULL) {
char *key = emalloc(strlen(str) + 1);
strcpy(key, str);
h->key[remainder] = key;
h->frequencies[remainder] = 1;
h->num_keys++;
}
/*if you find the string you were looking for,
increment the frequency at the position
and return the frequency*/
if (strcmp(str, h->key[remainder]) == 0) {
h->frequencies[remainder]++;
return h->frequencies[remainder];
}
if (h->key[remainder] != NULL && h->capacity == i) {
i = 0;
}
}
}
/*if you have kept looking for an open space but there isnt one,
the hash table must fu*/
return 0;
}
int htable_search(htable h, char *str) {
/*create an initialise, a value to hold the number of collisions we have when looking for our key*/
int collisions = 0;
unsigned int index = htable_word_to_int(str);
/*calculate the position at which we should start looking for our key*/
int remainder = index%h->capacity;
/*while there is an item at that position, but it isn't the key, and we haven't yet checked the entire hash table*/
while (h->key[remainder] != NULL && strcmp(str, h->key[remainder]) != 0 && h->key[remainder] != h->key[h->capacity]) {
/*increment our position to look for the next cell*/
h->key[remainder]++;
/*increment the number of collisions we've had so far*/
collisions++;
}
/*if our number of collisions == the hashtable capacity*/
if(collisions == h->capacity) {
/*then out hashtable was full, did not contain our key, so we should return 0*/
return 0;
}
else {
/*else return the frequency at our final position*/
return h->frequencies[h->capacity];
}
}
#include <stdio.h>
#include <stdlib.h>
#include "mylib.h"
#include "htable.h"
int main(void) {
htable h = htable_new(113);
char word[256];
char op;
/*We must have a space before the %c*/
while(2 == scanf(" %c %255s", &op, word)) {
if ('+' == op) {
htable_insert(h, word);
}
else if ('?' == op) {
printf("%d %s\n", htable_search(h, word), word);
}
}
htable_free(h);
return EXIT_SUCCESS;
}
我已经包含了上面的 mylib.c。
+ sociable
+ galleries
+ Russia
+ screamer
+ thickness
+ combed
+ escorted
+ revocable
+ digressed
+ Malawi
+ infringing
+ onslaught
+ files
+ kidded
+ unsound
+ tied
+ Ottawa
+ puzzles
+ build
+ necrosis
+ admire
+ cupful
+ brokers
+ segregation
+ Capet
+ Georges
+ bran
+ binders
+ zebras
+ contented
+ keypad
+ snowily
+ replaced
+ dominating
+ outright
+ Latinizers
+ invalidity
+ wakes
+ diversification
+ Riemannian
+ leadings
+ rhythmically
+ gentler
+ swarthy
+ disconnects
+ factoring
+ sequences
+ tiring
+ attendances
+ unloaded
? insincere
? constants
? unordered
? Toland
? butterfly
? suburban
? overtone
? Hauser
? numbers
? disadvantageous
? saintly
? Dutton
? homomorphic
? corporation
? climaxes
? dietitian
? manifestly
? greyest
? challenge
? tentacle
? Bernice
? bottle
? involve
? resisted
? wholesale
? trustworthiness
? Poole
? fourfold
? relentlessly
? fittingly
? doctorates
? cowlick
? Missoula
? curtsy
? calmness
? reallocate
? bossed
? scarce
? catheters
? regained
? autographing
? unobservable
? apprise
? lancer
? chicken
? crunches
? scrambled
? reared
? pealing
? violate
? sociable
? galleries
? Russia
? screamer
? thickness
? combed
? escorted
? revocable
? digressed
? Malawi
? infringing
? onslaught
? files
? kidded
? unsound
? tied
? Ottawa
? puzzles
? build
? necrosis
? admire
? cupful
? brokers
? segregation
? Capet
? Georges
? bran
? binders
? zebras
? contented
? keypad
? snowily
? replaced
? dominating
? outright
? Latinizers
? invalidity
? wakes
? diversification
? Riemannian
? leadings
? rhythmically
? gentler
? swarthy
? disconnects
? factoring
? sequences
? tiring
? attendances
? unloaded
这是我传入的文件的内容。我的插入方法有效，但如果需要，我也可以包含它。
【问题讨论】：
-
由于您没有向我们展示任何打印任何内容的代码，也没有向我们展示函数
htable_word_to_int()，并且由于我们不知道您的数据文件中有什么，因此我们不知所措可能出了什么问题。请制作一个SSCCE — 一个简短、独立、完整（编译）的示例。 -
这不是错误...这是此调用的输出：
printf("%d %s\n", htable_search(h, word), word); -
我看了之后才意识到，但是当我在命令行中运行程序时它确实会崩溃，因为它会打印出 0 insirere
-
@courtney 您正在从
unsigned int转换为signed int以计算remainder。验证值是否正常。 -
@courtney 还要检查以确保
h->key[remainder]++;是进行线性探测的正确方法。