String indexOf() and lastIndexOf() Method

The String object indexOf() method gives you the ability to search for the first instance of a particular character value in a String. You can also look for the first instance of the character after a given offset. The lastIndexOf() method lets you do the same things from the end of a String.

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In this case,

firstClosingBracket

equals 5, because the first

>

character is at position 5 in the String (counting the first character as 0). If you want to get the second closing bracket, you can use the fact that you know the position of the first one, and search from

firstClosingBracket + 1

as the offset, like so:

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Source: String indexOf() and lastIndexOf() Method | Arduino Documentation | Arduino Documentation

sudo systemd-resolve --set-dns=8.8.8.8 --interface=<interface name>

Source: networking – DNS issues after upgrading to 20.04 – Ask Ubuntu

int is_valid_fd(int fd)
{
    return fcntl(fd, F_GETFL) != -1 || errno != EBADF;
}

Source: c – How to check if a given file descriptor stored in a variable is still valid? – Stack Overflow