[Konstantinos]

Assuming it's not called by a timer or Call Local/Remote Function, you don't need to use forward/public for it.

pawn Код:

if (!AddReportToken(playerid))
{
    // the file couldn't be opened..
}
else
{
    // everything is fine
}

pawn Код:

AddReportToken(playerid) 
{
    new
        sz_FileStr[32 + MAX_PLAYER_NAME],
        sz_playerName[MAX_PLAYER_NAME],
        i_timestamp[3],
        File: fPointer;
    
    GetPlayerName(playerid, sz_playerName, MAX_PLAYER_NAME);
    getdate(i_timestamp[0], i_timestamp[1], i_timestamp[2]);
    
    format(sz_FileStr, sizeof(sz_FileStr), "admins/rtokens/%s[%d'%d'%d]", sz_playerName, i_timestamp[1], i_timestamp[2], i_timestamp[0]);
    if(fexist(sz_FileStr)) // checking if exists to open the file with io_read, else it will crash the server
    {
        fPointer = fopen(sz_FileStr, io_read);
        if (!fPointer) return 0; // return 0 and don't allow fPointer to be passed as argument and cause the crash
        fread(fPointer, sz_playerName);
        fclose(fPointer);
        
        new
            i_tokenVal = strval(sz_playerName);
        
        format(sz_playerName, sizeof(sz_playerName), "%i", i_tokenVal + 1);
        fPointer = fopen(sz_FileStr, io_write);
        if (!fPointer) return 0; // return 0 and don't allow fPointer to be passed as argument and cause the crash
        fwrite(fPointer, sz_playerName);
        fclose(fPointer);
    }
    else 
    {
        fPointer = fopen(sz_FileStr, io_write);
        if (!fPointer) return 0; // return 0 and don't allow fPointer to be passed as argument and cause the crash
        fwrite(fPointer, "1");
        fclose(fPointer);
    }
    return 1;
}