Does Matlab have a function which is similar with sizeof in C?
조회 수: 33 (최근 30일)
이전 댓글 표시
For example, if I type sizeof('double'), the function can give me 8. Let me know whether Matlab has a function working similarly with sizeof in C language.
댓글 수: 2
Steven Lord
2018년 3월 28일
How would you use such a function if it existed? You don't need to allocate memory yourself like you do in C, instead you should use functions like zeros, ones, etc. to preallocate your arrays.
mysiak
2019년 11월 8일
For example when reading custom binary files.
I created simple binary file where all elements are of say 64bit long int64. Now I want to read such binary file in matlab with fread. I want to use fseek in order to navigate through the file, but I need to move in chunks of data which correspond to meaningful frame in my applicatio, say 5 numbers of int64.
So the fseek looks like fseek(fileid, 5*8, 'cof');
Then I use fread like fread(fileID,5,'int64')
Now it would be good if the 5*8 in fseek could be replaced by 5 *sizeof('int64') since matlab is aware of the int64 type. So the number 8 should be tied to int64 type.
답변 (3개)
Jan
2018년 3월 28일
편집: Jan
2021년 4월 13일
A cheap method would be:
function S = sizeof(V)
switch lower(V)
case {'double', 'int64', 'uint64'}
S = 8;
case {'single', 'int32', 'uint32'}
S = 4;
case {'char', 'int16', 'uint16'}
S = 2;
case {'logical', 'int8', 'uint8'}
S = 1;
otherwise
warning('Jan:sizeof:BadClass', 'Class "%s" is not supported.', V);
S = NaN;
end
end
댓글 수: 0
Horshack Horshack
2021년 4월 10일
편집: Horshack Horshack
2021년 4월 12일
Edit: Oops, this doesn't work in Matlab, only Octave.
I simply cast an arbitrary constant value (zero) to the type and then take the size of the lvalue result. Examples:
sizeof(uint8(0))
sizeof(uint16(0))
sizeof(uint32(0))
sizeof(double(0))
Output:
1
2
4
8
댓글 수: 0
참고 항목
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!