如何在用C编程语言读入数组之前嗅探二进制文件中的记录数？

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

typedef struct {
    int id;
    float value;
} Record;

int main() {
    Record records[] = {
        {1, 1.23},
        {2, 4.56},
        {3, 7.89},
    };
    int num_records = sizeof(records) / sizeof(records[0]);

    FILE *file = fopen("records.bin", "wb");
    if (file == NULL) {
        printf("Error opening file!\n");
        exit(1);
    }

    fwrite(records, sizeof(Record), num_records, file);
    fclose(file);

    return 0;
}

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

typedef struct {
    int id;
    float value;
} Record;

int main() {
    FILE *file = fopen("records.bin", "rb");
    if (file == NULL) {
        printf("Error opening file!\n");
        exit(1);
    }

    // 获取文件大小
    fseek(file, 0, SEEK_END);
    long file_size = ftell(file);
    fseek(file, 0, SEEK_SET);

    // 计算记录数
    int num_records = file_size / sizeof(Record);

    // 读取数组
    Record *records = (Record *) malloc(file_size);
    fread(records, sizeof(Record), num_records, file);
    fclose(file);

    // 输出记录
    for (int i = 0; i < num_records; i++) {
        printf("Record %d: ID = %d, Value = %.2f\n", i + 1, records[i].id, records[i].value);
    }

    free(records);
    return 0;
}