Extract dates in various formats from string in R

I need to quickly extract dates from character vectors. I have 2 main issues:

• Various date formats (European and American, alphanumeric and numeric...)
• Multiple dates in each vector.

My vectors are something as follows:

c("11/09/2016 Invoice Number . Date P.O. # Amount Discount Paid Amount 2017/015 10/28/2016 CC6/ $50,000.00 $0.00 $50,000-00 2017/016 10/28/2016 CC67 $50,000.00 $0.00 $50,000-00 2017-017 10/28/2016 CC67 $50,000.00 . $0.00 $50,000.00 TOTALS: $150,000.00 $0.00 $150,000.00     ")

I have tried using parse_date and strptime without success. I do not know anything about the regex syntax and do not really have time to dig into it.

Warmly thank you for your help.