You first need to split the string using the semi-colon as the separator,. That will give you a string of numbers for each row. Then split each substring using the comma as separator which will give the numbers for each column. You can then allocate the array for the matrix. You then need to take each number in turn, convert it to a double value and store it in the relevant cell of the matrix. See
basic_string Class | Microsoft Docs[
^] to see how to find the separator characters.