C函数fwrite（）未写入文件

Question

I'm trying to write structures from tempGroupFile into GroupFile . fwrite() returns 1, when writing, but actually no data is written in the file GroupFile . Function printRec() prints out the structure on the screen. data is a variable of structure. File GroupFile is empty after these operations. Code:

GWTemp = fopen(tempGroupFile, "rb");
GW = fopen(GroupFile, "wb"); 
if((GW == NULL) || (GWTemp == NULL))
{
    puts("Failed to open file.");
    fflush(stdin);
    getchar();
    return 0;
}
while(fread(&data, sizeof data, 1, GWTemp))
{
    if(fwrite(&data, sizeof data, 1, GW))
    {
        printRec(data);
    }
}

Answer 1

You need to close the file using fclose(GW) after the while loop. This makes sure all buffers are flushed so the file is written.