动态分配的指针数组可自行重写

Question

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

例：

从word.txt中读取

apple
orange
apple
banana
orange
apple

写入frequencys.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，我只是尝试获取分配的第一个值（一个苹果）。 我遇到的问题是，当我尝试分配动态数组的第一个值时，wordarray-> word的值随文件中的每次读取而变化，但应该保留为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

任何建议表示赞赏。

Answer 1

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

当前wordarray[0]->word是指向buffer的指针，因此，每当您运行fscanf(fp,"%s",buffer)行时fscanf(fp,"%s",buffer)您都会更改其值

**不要忘记最后释放strdup内存

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

Answer 2

另外，您不知道size是多少。 首先，您可以扫描文件并找出大小：

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