Question

我正在尝试编写一个程序来查找文件中的单词频率（words.txt），使用动态分配的指针数组来存储单词和单词出现的频率并将结果打印到另一个文件（frequencies.txt）。

示例：

阅读words.txt

apple
orange
apple
banana
orange
apple

写入频率.txt：

3 apple
2 orange
1 banana

这是程序

#include <stdio.h>
#include <string.h>
#include<stdlib.h>

struct wordfreq 
{
  int count;
  char *word;
};

typedef struct wordfreq wordfreq;

int main(int argc, char *argv[])
{
    wordfreq **wordarray;
    int size = 1, i, j, x, compare;
    char buffer[100];
    FILE *fp;

    if ( argc != 3 )
    {
        fprintf(stderr,"!!!ERROR!!!\nNUMBER OF MISSING PARAMETERS: %d\n", 3-argc);
        exit(-1);
    }

    fp = fopen(argv[1],"r");
    if ( fp == NULL )
    {
        perror(argv[1]);
        exit(-1);
    }

    wordarray = (wordfreq**)malloc(size*sizeof(wordfreq*));

    for(i = 0; i < size; i++)
    {
        wordarray[i] = (wordfreq *) malloc(sizeof(wordfreq*));
        wordarray[i]->word = "!";
        wordarray[i]->count = 0;
    }

    while(fscanf(fp,"%s",buffer) == 1)
    {
        printf("Word: %s\n", buffer);

        if(wordarray[0]->word == "!")
        {
            wordarray[0]->word = buffer;
            wordarray[0]->count = 1;
        }

        //Continued coding

        for(x = 0; x < size; x++)
        {
            printf("%d %s\n", wordarray[x]->count, wordarray[x]->word);
        }
        printf("\n");
    }

    //wordarray = realloc(wordarray,size*sizeof(wordfreq*));

    fclose(fp);

    fp = fopen(argv[2], "w");
    if ( fp == NULL )
    {
        perror(argv[1]);
        exit(-1);
    }

    for(i = 0; i < size; i++)
    {
        fprintf(fp, "%d %s\n", wordarray[i]->count, wordarray[i]->word);
    }

    fclose(fp);

    free(wordarray);

    return 0;
}

现在我只想尝试分配第一个值（1个苹果）。我遇到的问题是，当我尝试分配动态数组的第一个值时，wordarray-＆gt; word的值会随着每次从文件读取而改变，但它应该保留为apple：

Word: apple
1 apple

Word: orange
1 orange

Word: apple
1 apple

Word: banana
1 banana

Word: orange
1 orange

Word: apple
1 apple

Results:
1 apple

感谢任何建议。

Answer 1

将wordarray[0]->word = buffer替换为wordarray[0]->word = strdup(buffer)

目前wordarray[0]->word是指向buffer的指针，因此每次运行fscanf(fp,"%s",buffer)行时都会更改它的值

**不要忘记最后释放strdup记忆

for(i = 0; i < size; i++)
{
    free(wordarray[i]->word);
}

Answer 2

另外，你不知道size是什么。首先，您可以扫描文件并找出尺寸：

int size = 0;
while (!feof(fp))
{
    fscanf(fp, "%s\n", buffer);
    size++; //you have this many lines in the files
}
rewind(fp);

动态分配的指针数组保持自我重写

2 个答案: