How to convert time stamp 11:21:17.155 into seconds in MATLAB??

I am quite not sure how to covert time stamps of this sort into seconds in MATLAB. Any help is appreciated.

Thank you

[Mathieu NOE]

hello

try this :

a = '11:21:17.155';
n = split(a,':');
duration_seconds = str2num(n{1})*3600+str2num(n{2})*60+str2num(n{3})

[Stephen23]

a = '11:21:17.155';
b = [60*60,60,1]*str2double(split(a,':'))

b = 
                 40877.155

Answer 1

[Stephan]

format longG
a = '11:21:17.155';
b = seconds(duration(a,'InputFormat','hh:mm:ss.SSS'))

results in:

b =

                 40877.155

Answer 2

[Stephen23]

The most efficient solution:

a = '11:21:17.155';
b = [60*60,60,1]*sscanf(a,'%f:')

b = 
                 40877.155