objective c - EXC_BAD_ACCESS (code = 2, adress = 0x0) while changing value of boolean -

what i'm trying do

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in app, got sql-lite database wrote methodes. callback of method boolean. true = write data, false = not write data. code dosn't show error's in x-code should right.

question

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in method define boolean , set null. afterwards have if-clause, check's if data written db, , change defined boolean true or false. throws me error:exc_bad_access (code = 2, address = 0x0)

the point is, don't understand why error coming along. guys please tell me, i'm doing wrong , how can solve it. you'll find code down here:

code

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    - (bool *) createlogin:(nsinteger *)user_id                    usr: (nsstring *)username                    pwd: (nsstring *)password                   date: (nsdate *)last_login{      bool *returnvalue = null;      self.ivo_db = [[ivo_database alloc] init];      if((sqlite3_open_v2([[ivo_db getwritabledatabase] utf8string], &sqldb, sqlite_open_readwrite, null) != sqlite_ok)){      nslog(@" %s couldn't open writable database '%s' (%1d)", __function__, sqlite3_errmsg(sqldb), sqlite3_errcode(sqldb));      }else{         int userid = *user_id;         nsstring *sqlstring = [nsstring stringwithformat:@"insert tbl_login (user_id, username, password, last_login) values (%d,'%@','%@','%@')", userid, username, password, last_login];      const char *putlogindata = [sqlstring utf8string];     sqlite3_stmt *sqlstatement;      if(sqlite3_prepare(sqldb, putlogindata, -1, &sqlstatement, null) != sqlite_ok)     {         nslog(@"%s sqlite_error while preparing statement '%s' (%1d)", __function__, sqlite3_errmsg(sqldb), sqlite3_errcode(sqldb));         *returnvalue = no;     }else{      sqlite3_step(sqlstatement);     sqlite3_finalize(sqlstatement);      int lastinsert = sqlite3_last_insert_rowid(sqldb);     nslog(@"lastinsertid:%d", lastinsert);     sqlite3_close(sqldb);     *returnvalue = yes;     }    }     return returnvalue; } 

bool *returnvalue = null; /* ... */ *returnvalue = yes; 

you first create pointer bool. set address it's pointing to null. try set value of address it's pointing to yes.

or short: try write @ adress 0x00. won't work.

you want use bool. primitive type, without pointer.

- (bool) createlogin:(nsinteger *)user_id                usr: (nsstring *)username                pwd: (nsstring *)password               date: (nsdate *)last_login{     bool returnvalue = no;     /* ... */     returnvalue = yes;     /* ... */     return returnvalue; }