MATLAB: Str2double/str2num

str2doublestr2num

day='0001'; str2double(day) would give me 1 as answer, how do I get 0001 exact four number of digits for instance?

Best Answer

Floating point variables do not have leading 0's physically stored in memory (not counting the denormalized numbers of course). So 0001 and 1 are stored exactly the same in memory. If you want to display the leading 0's then you need to use a format that specifies that on print out. E.g.,

>> day = '0001'
day =
0001
>> d = str2double(day)
d =
     1
>> fprintf('%04d\n',d)
0001

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MATLAB: How to change the field width of an exponential notation

Given >=2 digits, ensure >=3 digits:

>> val = 3.45866636216603e2;
>> str = sprintf('%.14e',val)
str =
3.45866636216603e+02
>> str = regexprep(sprintf('%.14e',val),'(?<=\D)\d\d$','0$&')
str =
3.45866636216603e+020

Given >=1 digits, ensure >=3 digits:

>> str = regexprep(sprintf('%.14e',val),{'(?<=\D)\d$','(?<=\D)\d\d$'},'0$&')
str =
3.45866636216603e+020

A general solution that can provide any number of digits:

>> num = 3; % required number of digits
>> fun = @(s)sprintf('%0*u',num,sscanf(s,'%u'));
>> str = regexprep(sprintf('%.14e',val),'\d+$','${fun($&)}')
str =
3.45866636216603e+020

MATLAB: Str2double / str2num / conversion confusion

reason is that you are doing str2double 2x. so area already has the text being converted to a double. then you try to convert a double to double in your fprintf.

simple test:

x='1';
str2double(str2double(x))

will result to NaN

no need for the str2double in the fprintf statement

Best Answer

Related Solutions

MATLAB: How to change the field width of an exponential notation

MATLAB: Str2double / str2num / conversion confusion

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