Question

我对第10章的练习10有一个问题，在Stephen Cochan编写的C编程一书中。

问题是：

编写一个名为dictionarySort的函数，用于对字典进行排序，如中所定义程序10.9和10.10，按字母顺序排列。

虽然我认为排序算法没有问题，但是我命名存储字符的临时变量temp的方式肯定有问题。我不知道我在哪里错了，我多次尝试过，现在我很困惑。

我的代码如下。你可以忽略这样一个事实，即我没有写入另一个函数。当我看到自己的错误时，我会发挥作用。就目前而言，为了简单起见，我在main中拥有了我需要的一切。

#include <stdio.h>

struct entry {
    char word[15];
    char definition[64];
};

int main (void) {
    // void dicionarySort (struct entry *dictionary[], const int entries);

    struct entry dictionary[100] = {
        { "aardvark", "a burrowing African mammal"        },
        { "ahoy",     "a nautical call of greeting"       },
        { "affix",    "to append; attach"                 },
        { "addle",    "to become confused"                },
        { "agar",     "a jelly made from seaweed"         },
        { "aerie",    "a high nest"                       },
        { "acumen",   "mentally sharp; keen"              },
        { "aigrette", "an ornamental cluster of feathers" },
        { "abyss",    "a bottomless pit"                  },
        { "ajar",     "partially opened"                  }
    };

    int i, j, entries = 10;
    struct entry temp[10];

    printf("Dictionary before sorting:\n");
    for (i = 0; i < entries; ++i)
        printf("Word: \"%s\" \t Definition: \"%s\"\n",
               dictionary[i].word, dictionary[i].definition);

    //dictionary[100] = dicionarySort(&dictionary, 10);

    for (i = 0; i < entries - 1; ++i)
        for (j = i + 1; j < entries; ++j)
            if (dictionary[i].word > dictionary[j].word) { // if previous word is higher than next word..
                temp[i] = dictionary[i];
                dictionary[i] = dictionary[j];
                dictionary[j] = temp[i];
            } // ..exchange their positions in the dictionary

    printf("\nDictionary after sorting:\n");
    for (i = 0; i < entries; ++i)
        printf("Word: \"%s\" \t Definition: \"%s\"\n",
               dictionary[i].word, dictionary[i].definition );

    printf("\n");

    return 0;
}

我得到的输出是：

Dictionary before sorting:
Word: "aardvark"         Definition: "a burrowing African mammal"
Word: "ahoy"     Definition: "a nautical call of greeting"
Word: "affix"    Definition: "to append; attach"
Word: "addle"    Definition: "to become confused"
Word: "agar"     Definition: "a jelly made from seaweed"
Word: "aerie"    Definition: "a high nest"
Word: "acumen"   Definition: "mentally sharp; keen"
Word: "aigrette"         Definition: "an ornamental cluster of feathers"
Word: "abyss"    Definition: "a bottomless pit"
Word: "ajar"     Definition: "partially opened"

Dictionary after sorting:
Word: "aardvark"         Definition: "a burrowing African mammal"
Word: "ahoy"     Definition: "a nautical call of greeting"
Word: "affix"    Definition: "to append; attach"
Word: "addle"    Definition: "to become confused"
Word: "agar"     Definition: "a jelly made from seaweed"
Word: "aerie"    Definition: "a high nest"
Word: "acumen"   Definition: "mentally sharp; keen"
Word: "aigrette"         Definition: "an ornamental cluster of feathers"
Word: "abyss"    Definition: "a bottomless pit"
Word: "ajar"     Definition: "partially opened"

你可以看到没有发生任何事情，字典也没有排序。我对此非常困惑。我已经成功实现了一个对数组进行排序的程序，但我不知道我应该在这做什么。我不知道我哪里错了。如果有人能给我一个提示，那将对我有所帮助！

Answer 1

与

if ( dictionary[i].word > dictionary[j].word )

你正在比较地址（dictionary[i].word是字符串第一个字符的地址），而不是词汇值。

从这个角度来看，字典已经完全排序（因为元素存在于升序的内存地址中）。

将其更改为：

if (strcmp(dictionary[i].word, dictionary[j].word) > 0)

它可能会起作用。

Answer 2

尝试这种方式：）

for ( i = 0; i < entries - 1; ++i )
    for ( j = i + 1; j < entries; ++j )
        if ( strcmp(dictionary[i].word, dictionary[j].word)>0 ){ // if previous word is higher than next word..
            temp[i] = dictionary[i];
            dictionary[i] = dictionary[j];
            dictionary[j] = temp[i];
        } // ..exchange their positions in the dictionary

你写的代码比较了每个单词的指针！

更好地查看代码，我建议你做两件事：

声明：

struct entry temp;

而不是：

struct entry temp[10];

代码变为：

for ( i = 0; i < entries - 1; ++i )
        for ( j = i + 1; j < entries; ++j )
            if ( strcmp(dictionary[i].word, dictionary[j].word)>0 ){ // if previous word is higher than next word..
                temp = dictionary[i];
                dictionary[i] = dictionary[j];
                dictionary[j] = temp;
            } // ..exchange their positions in the dictiona

Answer 3

您可以重用同一章中使用的compareStrings函数来比较字典中的单词

// Function to compare two character strings

int  compareStrings (const char  s1[], const char  s2[])
{
    int  i = 0, answer;

    while ( s1[i] == s2[i] && s1[i] != '\0'&& s2[i] != '\0' )
        ++i;

    if ( s1[i] < s2[i] )
        answer = -1;               /* s1 < s2  */
    else if ( s1[i] == s2[i] )
        answer = 0;                 /* s1 == s2 */
    else
        answer = 1;                 /* s1 > s2  */

    return answer;
}

然后您的例程将变为：

for ( i = 0; i < entries - 1; ++i )
        for ( j = i + 1; j < entries; ++j )
            if ( compareStrings (dictionary[i].word, dictionary[j].word) == 1 ) {
                temp[i] = dictionary[i];
                dictionary[i] = dictionary[j];
                dictionary[j] = temp[i];
            }

从那里您可以构建dictionarySort函数

排序字典，用C编程，Stephen Kochan，第10章，练习10

3 个答案: