basic_string::find_first_of

size_type find_first_of(E c, size_type pos = 0) const;
size_type find_first_of(const E *s, size_type pos = 0) const;
size_type find_first_of(const E *s, size_type pos, size_type n) const;
size_type find_first_of(const basic_string& str,
    size_type pos = 0) const;

Each member function finds the first (lowest position) element of the controlled sequence, at or after position pos, that matches any of the elements in the operand sequence specified by the remaining operands. If it succeeds, it returns the position. Otherwise, the function returns npos.

See the related sample program.