readme.txt

来自「A template solution for C++ database dev」· 文本 代码 · 共 51 行

Use this class in the following manner (where MY_TYPE is a class or structure written by you)

Adding a record:
*************
MY_TYPE mt;
// Set values of mt member variables
DataStore<MY_TYPE> ds("my.dat");
if(ds.Open()) {
    if(ds.AddRecord(mt)) {
       cout<<"Record saved"<<endl;
    }else {
       cout<<"Failed to save record"<<endl;
   }
ds.Close();
}else {
cout<<"Failed to open file"<<endl;
}
*********************************
~~~~~~~~~~~~~~~~~~~~~~~~~~
Finding number of records in a data file:
******************************
DataStore<MY_TYPE> ds("my.dat");
if(ds.Open()) {
     unsigned long recs = ds.GetRecordCount();
}
***********************************

~~~~~~~~~~~~
Deleting a record:
*************
unsigned long index = 0;
for(unsigned long i=0;i<recs;i++) {
    mt = ds.FindRecord(i);
     // compare a field of mt against a search value
     if (comparison is true) {
    break;
   }else {
     index++;
   }
}
ds.DeleteRecord(index);
// ds.ModifyRecord(new_mt,index);
ds.Close();
***********************************

DataStore has a member function called GetNextRecordNo() which can be used to generate
a unique long id for the next record to be written.
This function can be used for getting an id for uniquely identifying a record in the file.
For this a class that serializes itself using DataStore should have an unsigned long field in it.