Question

I have a array define as short FavList[300];

I try to load all 1’s in it, save it.
Then out in all 0’s and load it.

After I read in thew data, it is still all 0.s, and did not get loaded with all ones.

code

-(void)Load{

    // put in all 1's
    for(int i=0; i<AMOUNT_OF_IMAGES; i++)
        FavList[i]=1;  

    // save it
    [self Save];

    // put in all 0's
    for(int i=0; i<AMOUNT_OF_IMAGES; i++)
        FavList[i]=0; 

    // load it
    NSString *path = [NSString stringWithFormat:@"%@/test3.bin", [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]];
    NSData *read = [NSData dataWithContentsOfFile:path];
    if (read==nil)
    {
        // it has not been save whete, set up a empty favret
        for(int i=0; i<AMOUNT_OF_IMAGES; i++)
            FavList[i]=0;     
    }
    else
    {
    // transfer to our arrow
     NSRange test = {0,sizeof(FavList)};
    [read getBytes:&FavList range:test];

    // what happen, the data is still 0, not 1?????????
   }

} 


-(void)Save{
    // get file name
    NSString *path = [NSString stringWithFormat:@"%@/test3.bin", [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]];

    NSMutableData *data = [NSMutableData dataWithLength:sizeof(FavList)];
    [data appendBytes:&FavList length:sizeof(FavList)];
    [data writeToFile:path atomically:YES];     

}

Answer 1

I use [data appendBytes:&FavList length:sizeof(FavList)]; to add the data. The append added the data at the end. It was created with a size of FavList, thus the begging was all zeros with the data stored at the end.

When the data was read in it was the begging and just zeros