C++ 用C语言计算文本文件中的整数个数

我制作了一个名为qsort.txt的文本文件，并在文件中写入了任意多个整数(在我的例子中，准确地说是35个整数).我的目标是计算该文件中有多少个整数，将它们放入由malloc()定义的数组中，并使用qsort()对它们进行排序.之后，我希望将排序后的数字写入一个名为sorted.txt的文本文件中.

这是我的代码，但显然不像预期的那样工作.此外，我想更灵活的代码，所以在FILE *fa = fopen(argv[1], "r+")是argv[1]，这样我就可以把任何其他文本文件进行排序.无论如何，我的问题是我不知道如何计算文件中有多少个整数.

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

int compare(const void *a, const void *b) {
    if (*(int*)a < *(int*)b)
        return -1;
    else if (*(int*)a > *(int*)b)
        return 1;
    else
        return 0;
}

int main(int argc, char **argv) {

    FILE *fa = fopen(argv[1], "r+");
    if (!fa)
        exit(1);
    FILE *fb = fopen("sortirano.txt", "w+");

    long duljina, i;
    long *ptr, *zapis;
    long count = 0;

     while (!feof(fa))
         count++;

     printf("%lu\n", count);

     fseek(fa, 0, SEEK_END);
     duljina = ftell(fa);
     fseek(fa, 0, SEEK_SET);

     ptr = (long *)malloc(sizeof(long));

     while (!feof(fa)) {
         fscanf(fa, "%lu", ptr);
         count++;
     }
     printf("count: %lu\n", count);
     for (i = 0; i < count; i++)
         printf("%lu ", ptr[i]);

    printf("\n");

    free(ptr);

    fclose(fa);
    fclose(fb);

    return 0;
}

EDIT:个

这是我的新代码，它更简单:

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

int compare(const void *a, const void *b) {
    if (*(long*)a > *(long*)b)
        return 1;
    if (*(long*)a < *(long*)b)
        return -1;
    else
        return 0;
}

int main() {
    FILE *fa = fopen("qsort.txt", "r"); assert(fa != NULL);
    FILE *fb = fopen("sorted.txt", "w+"); assert(fa != NULL);

    long *ptr;
    long save;
    long count = 0;
    long i;
    long k;

    while ((fscanf(fa, "%ld", &save)) == 1) //number of elements
        prebroji++;

    printf("count: %ld\n", count); //checking how many elements i have, just to make sure it works ok

    ptr = (long *)malloc(count * sizeof(long)); //mallociranje

    for (i = 0; i < count; i++)
        fscanf(fa, "%ld", &ptr[i]);

    for (i = 0; i < count; i++) //checking if numbers were saved at malloc array
        printf("%ld ", ptr[i]);

    qsort(ptr, count, sizeof(long), compare);

    for (i = 0; i < count; i++) //checking if sorted correctly
        printf("%ld ", ptr[i]);

    for (i = 0; i < count; i++)
        fprintf(fb, "%ld", ptr[i]);

    printf("\n");

    free(ptr);
    fclose(fa);
    fclose(fb);

    return 0;
}

但它不起作用:我得到的都是打印的零.