string::find_first_not_of (1 of 2 overloads)

Find the first occurrence of any of the characters not within the string.

std::size_t
find_first_not_of(
    string_view sv,
    std::size_t pos = 0) const;

Returns the index corrosponding to the first character of {begin() + pos, end()) that is not within sv if it exists, and npos otherwise.

Linear.

The first occurrence of a character that is not within sv within the string starting at the index pos, or npos if none exists.

Name	Description
`sv`	The characters to ignore.
`pos`	The index to start searching at. The default argument for this parameter is `0`.

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