string to number conversion with mixed values

i have two strings

'index_N=10'

and

'index_M=5'

in a file.

how can i get only numbers N =10 and M=5. from these strings

[Walter Roberson]

Duplicated by later http://www.mathworks.com/matlabcentral/answers/309184-convert-string-containing-number-to-number-only and requires merging

Answer 1

[Massimo Zanetti]

str1 = 'index_N=10'
str2 = 'index_M=5'

sub1 = str1(7:end)
sub2 = str(7:end)

[lafnath p]

IT GIVES 10 , 5 AS STRINGS.

but i want those values as integers

[Walter Roberson]

str2double() or sscanf()

Answer 2

[Guillaume]

It looks like you're asking two things:

• how to create variables named from the content of a string,
• how to get the index string and number from your input string.

The first part is an extremely bad idea, so I won't show you how to do it because it always lead to bad practice, and complicated, buggy and unmaintainable code. If you want to store these names, store them in a cell array, table, or containers.Map.

To extract name and number from your input:

tokens = regexp(inputstring, 'index_(.)=(\d+)', 'tokens', 'once');
indexname = tokens{1}
indexvalue = str2double(tokens{2})

%optionally store them in a map created with
%map = containers.Map;
map(indexname) = map(indexvalue)

%or store them in a table created with:
%t = table({}, [], 'VariableNames', {'IndexName', 'IndexValue'})
t = [t; table(indexname, indexvalue, 'VariableNames', {'IndexName', 'IndexValue'})]