用 C 编写和读取二进制文件

Question

我正在编写一个 C 代码，它写入一些信号采样信息，然后读取它们并将它们存储到二进制文件中。我在写信息时得到了正确的输出，但在尝试读取它们时出现了错误。这是我的代码：

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

typedef struct {
    unsigned int sample_offset;
    double time;
    unsigned int date;
    unsigned char receiver_name[20];
    double sample_rate;
    unsigned int channel;
    unsigned int bits;
    unsigned char file_type[11];
    unsigned int freq_band;
    double channlel_bandwidth;
    double firmwire_version;
    double header_version;
} sampleInfo;

int main() {
    // Writing file
    FILE *fw;
    sampleInfo data = { 64, 0.55, 19, "Gadfly", 51.2, 2, 4, "Spreadsheet", 1,24, 1.0, 1.0 }, read_data;

    fw = fopen("sample.bin", "wb");
    if (!fw) {
        printf("Unable to open the file\n");
        return 1;
    } else {
        printf("Sample offset: %d bytes\n", data.sample_offset);
        printf("Capture time: %.2f seconds\n", data.time);
        printf("Date: %d October,2018\n", data.date);
        printf("Receiver name: %s\n", data.receiver_name);
        printf("Sample rate: %.2f Mega-samples per second\n", data.sample_rate);
        printf("Number of channels used: %d\n", data.channel);
        printf("Number of bits per I and Q sample: %d\n", data.bits);
        printf("File type: %s\n", data.file_type);
        printf("Frequency band per channel: L%d\n", data.freq_band);
        printf("Channel Bandwidth: %.fMHz\n", data.channlel_bandwidth);
        printf("Firm-wire version: %.1f\n", data.firmwire_version);
        printf("Header version: %.1f\n\n\n\n", data.header_version);
    }

    fwrite(&data, sizeof(sampleInfo), 1, fw);
    fclose(fw);

    // Reading file
    FILE *fr;
    fr = fopen("Sample.bin", "rb");
    if (!fr) {
        printf("Unable to open the file\n");
        return 1;
    } else {
        printf("Sample offset: %d bytes\n", read_data.sample_offset);
        printf("Capture time: %.2f seconds\n", read_data.time);
        printf("Date: %d October,2018\n", read_data.date);
        printf("Receiver name: %s\n", read_data.receiver_name);
        printf("Sample rate: %.2f Mega-samples per second\n", read_data.sample_rate);
        printf("Number of channels used: %d\n", read_data.channel);
        printf("Number of bits per I and Q sample: %d\n", read_data.bits);
        printf("File type: %s\n", read_data.file_type);
        printf("Frequency band per channel: L%d\n", read_data.freq_band);
        printf("Channel Bandwidth: %.fMHz\n", read_data.channlel_bandwidth);
        printf("Firm-wire version: %.1f\n", read_data.firmwire_version);
        printf("Header version: %.1f\n\n\n\n", read_data.header_version);
    }

    fread(&read_data, sizeof(sampleInfo), 1, fw);
    fclose(fr);

    return 0;
}

我对 C 语言比较陌生，所以在这方面有点挣扎。任何形式的帮助将不胜感激。提前致谢。

Answer 1

打印前阅读！

在打印文本之前，fread(&read_data,sizeof(sampleInfo),1, fr); 必须位于 else 分支中。

Answer 2

阅读语句有错别字：fread(&read_data, sizeof(sampleInfo), 1, fw); 应该读自fr，而不是fw：

fread(&read_data, sizeof(sampleInfo), 1, fr);

此外，您应该在打印read_data的内容之前阅读数据。

您还应该测试fwrite 和fread 的返回值，以验证I/O 操作是否成功。