in c plus lenge activity

$8\mathrm{.}6\mathrm{.}1$: Write a function that cleans a string containing an integer and converts it$.$

$577648\mathrm{.}3479862.$qx$3$zqy$7$

When reading data from a text file, it is common to see numbers such as $12,345,$ $$20,$ or $195*.$

Write a function that cleans a string containing digits by removing any characters that are not a digit or a $-$ sign. Then convert to an integer and return the result.