动态分配的指针数组不断重写自身

Question

我正在尝试编写一个程序来查找文件中单词的频率 (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：

阅读自words.txt

apple
orange
apple
banana
orange
apple

写入frequencies.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;
}

现在我只是试图获得分配的第一个值（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->word 的值会随着每次从文件中读取而改变，但它应该保持为 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

如有任何建议，我们将不胜感激。

Answer 1

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

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

** 最后不要忘记释放 strdup 内存

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

Answer 2

还有，你不知道size是什么。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);

动态分配的指针数组不断重写自身

Dynamically Allocated Array of Pointers Keeps Rewriting Itself

c

string

pointers

structure