Question

Function HEX is one of the core functions in sqlite

I would like to call the function from my objective-c code without actually creating a database in my app .. and so on.

What would be the simplest way to call the function with the least addition of classes?

I found lots of functions written in o-c that HEX a string. However, they are not correct as they produce results different from the HEX function of mysql.

Solution: Converting a string to its Hex value

+(NSString *) stringToHex:(NSString *)str
{
    NSString *aResult;
    sqlite3 *database;
    if(sqlite3_open(":memory:", &database) == SQLITE_OK) 
    {
        NSString *sqlStatement = [NSString stringWithFormat:@"select HEX('%@')",str];
        sqlite3_stmt *compiledStatement;
        if(sqlite3_prepare_v2(database, [sqlStatement cStringUsingEncoding:NSUTF8StringEncoding], -1, &compiledStatement, NULL) == SQLITE_OK) {
            while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
                aResult = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];
            }
        }
        sqlite3_finalize(compiledStatement);
    }
    sqlite3_close(database);
    return aResult;
}

Answer 1

You can open an in-memory db using sqlite3_open and use that. To do this, open a db with the file name :memory: (w/ the colons).

If you only want the hex function, you can also look into the source code of SQLite. It’s plain C and in the public domain.