Question

以下是数据的编写方式：

FILE* f = fopen(FILENAME, "ab");

if(ferror(f) != 0) {
    printf("fopen failed %d\n", ferror(f));
}

size_t written = 0;

written = fwrite(&key, sizeof(key), 1, f);
if(written != 1) {
    printf("fwrite wrote %d elements, should have been %d\n", written, 1);
}

written = fwrite(&value, sizeof(value), 1, f);
if(written != 1) {
    printf("fwrite wrote %d elements, should have been %d\n", written, 1);
}

if(ferror(f) != 0) {
    printf("fwrite failed %d\n", ferror(f));
}

fclose(f);

以下是数据的读取方式：

FILE* f = fopen(FILENAME, "rb");

if(ferror(f) != 0) {
    printf("fopen failed %d\n", ferror(f));
}

uint64_t key = 0;
uint64_t value = 0;
size_t read = 0;

while(!feof(f)) {
    read = fread(&key, sizeof(key), 1, f);
    if(read != 1) {
        printf("fread read %d elements, should have been %d\n", read, 1);
    }

    read = fread(&value, sizeof(value), 1, f);
    if(read != 1) {
        printf("fread read %d elements, should have been %d\n", read, 1);
    }

    if(ferror(f) != 0) {
        printf("fread failed %d\n", ferror(f));
    }

    if(key == 0 || value == 0) {
        printf("fread output was key = %llu, value = %llu\n", k, value);
    }

    if(key == arg) {
        fclose(f);
        return value;
    }
}

printf("EOF reached, returning 0\n");
fclose(f);
return 0;

现在就是这个难题：没有触发printf调试/错误语句。就我而言，我正确地打开和关闭文件，我正在编写和读取正确数量的（正确大小）元素，并且没有任何杂项错误输出。

但是，读取的值有时与写入的值不同。这种情况很少发生，也许每30到50次运行一次，但在这种情况下的影响是灾难性的，因为在我的情况下它会导致我的程序崩溃。这是我的调试语句中的一些输出直接在函数之外（应该没有代码可以以任何方式改变值）：

Saving key-value pair to store failed, wrote value 1930602754145344693, read value 7983440653331291317
File contents:
key 32385216, value 10451404324075904545
key 32385152, value 8261841165554445677
key 32384944, value 7948309595355207668
key 32384320, value 79834406533311291317

文件中没有重复的键（或值）。

你能给我任何指导如何调试这样的问题吗？对我而言，问题似乎不在我的计划之内，但我不确定是否会出现这种情况。我的操作系统是Windows 7 x64，而且我正在写入我的系统SSD磁盘，这应该不会有任何错误（我认为我写的文件实际上是由Windows一直缓存在RAM中的因为经常访问）。

C - fwrite写入无效数据

0 个答案: