Someone told me if i purchase the stock shares before ex dividend date but after announcement of dividend per share, i will not be entitled to the dividend. Is that true?

Nope, as long as it is before the ex-div date, you will receive it. If you purchase on or after the ex-div date, that div issue goes to the seller.

You will get the dividend if you purchase the stock before the ex dividend date. Also, if u sold off the stock before ex dividend date, you will not be entitled to the dividend.

Nope, you just need to buy before the XD date (ex-dividend date). If you sell before the XD date, you will not be entitled to the dividends, you have to hold onto the stock until after the ex-dividend date!

Buy before and do not sell before XD ex dividend, and you will get dividend