I know how it is possible to enter acute (á), grave (à), circumflex (â), and tilde (ã) diacritics with US international keyboard. You just enter one of the symbols ('`^~) and then a vowel.
Is it possible to enter macron (ā) and caron (ǎ) also some similar way?
What is the simplest way to enter these diacritics?
Not directly, no. As you can see from Microsoft's keyboard layout animation, hyperlinked below, there's no dead key combination for macron or caron.
In the worst case you can probably resort to Alt+numeric codes
— From http://www.personal.psu.edu/ejp10/psu/gotunicode/macron.html
Despite the caption these work in several programs and several versions of Windows (I tried in Vista WordPad)
The people at Wikipedia have collected a set of third-party keyboard layouts and utilities for Windows that they can use for writing macrons in Wikipedia articles.
Other methods I have seen mentioned for characters not in the keyboard:
As an aside only, because I do not know the answer for Windows: I have dead accents for macron and caron on my Linux keyboard, they are placed on the 3 and . keys for US International on Linux.
I also have them on my Colemak keyboard (both for X and for Windows, of course) on the m (for macron) and h (for háček) keys. I recommend this layout anyway, but it get ever more off-topic.
AltGr key. With Colemak, AltGr-H creates the dead caron accent, AltGr-M creates the dead macron. That is even identical for Windows and Linux, while the US International keyboard seems to be an extended version on Linux.
This doesn't work for the caron, but the macron is available in the English-Māori keyboard layout, which you can use in the same way you'd use US-International.
The macron is typed using ` as a dead key before a lower-case or upper-case vowel. There are no other dead keys: the layout is otherwise the same as standard US.
I know there are three "simple" ways of doing this (I recommend method 3):
Method 1: Enable Unicode input in Windows and learn the Unicode codes of the vowels. To enable Unicode input is already answered elsewhere in Stack Exchange (e.g., here and here). I find this method overpowered for this case.
Method 2: Autohotkey. It is an open Source software that allows you to create custom macros, key combinations and alike to extend the power of the keyboard. So install it, code the macros, run them and cnfigure the system to launch them at system startup or with a shortcut. I find this method requiring coding skills and being a power user.
Method 3: Pinyinput (or here in SourceForge). It is an open source software intended to write pinyin (romanized chinese), but the two marks you are interested in, macron and caron, are used for the 1st and 3rd tone marks in pinyin. You just need to type the vowel followed by 1 or 3, e.g., o1 becomes ō, a3 becomes ǎ. I think this is the easiest method for the common user, despite it requires an additional IME.
I'm using the US-international keyboard and I can type háčeks using Shift + Alternate Graph + Period/Greater-Than, followed by the letter that belongs below. If I need the macron, I hit Shift + Alternate Graph + Three/Hash, followed by the letter that belongs below.
However, there are several variants of the US international keyboard; Some of them lack the háček and the macron.
For macron and hatschek you can also use the Unicode block for Combining Diacritical Marks:
U+0304 (decimal 772) is for macron
U+030C (decimal 780) is for hatschek
In Microsoft Word you just enter the leading vowel first, then 0304 or 030C right followed by ALT+C.
In my Google searchbar I need to use the ̄ or ̌ function instead for the combining diacritical marks.
I don't know if it works on an US or UK keyboard, but for the German keyboard layout I have just found another way to enter macron and hatschek in MS word:
ALT GR+- for macron
Alt GR+^ for hatschek
on Linux US International, AltGR Unicode Combining layout to do a macron you can press Alt+Shift+~ after pressing the the vowel. Õk?
