Finding characters in a string / filename

How would I return as a double the number after the letter in the following file name? For instance, in the following, I would like to return 44 only.

'A123_T44_1.txt'

Answer 1

[Image Analyst]

If your filename naming protocol is fixed, so that the second number is always in position 7 and 8, you can use str2double():

fileName = 'A123_T44_1.txt';
number2 = str2double(fileName(7:8))

number2 = 44

[L'O.G.]

Thanks, but it's not fixed. It's whatever is after the T.

[Image Analyst]

So the format is letter, then any number of numbers, then '_T', then any number of numbers, then an underline, and finally some number of numbers? And you want the number between the first and second underline?

fileName = 'A123_T44_1.txt';
underlineLocations = strfind(fileName, '_');
number2 = str2double(fileName(underlineLocations(1) + 2 : underlineLocations(2)  - 1))

number2 = 44

It's just an alternative in case you find the scanf/regexp stuff too cryptic and want something more straightforward.

[L'O.G.]

Thank you so much for explaining all that.