CODEWITHSUNDEEP
stringmatlabascii
cs0815
cs0815

Reputation: 17408

transform string/char to uint8

Why does the expression:

test = cast(strtrim('3'), 'uint8')

produce 51?

This is also true for:

test = cast(strtrim('3'), 'int8')

Thanks.

Upvotes: 2

Views: 4833

Answers (3)

Jonas
Jonas

Reputation: 74940

Because 51 is the ASCII code for the character '3'.

If you want to transform the string to numeric 3, you should use

uint8(str2double('3'))

Note that str2double will ignore trailing spaces, so that strtrim isn't necessary.

EDIT

When a string is used in an numeric operation, Matlab automatically converts it to its ASCII value. For example

>> '1'+1
ans =
    50

Upvotes: 4

Ben A.
Ben A.

Reputation: 1039

This is because '3' is seen as an ASCII character to matlab. By casting as a signed or unsigned integer (8 bits in this case) you are asking Matlab to convert an ASCII '3' to a decimal number. In this case the decimal number is 51. If you want to look at more conversions here is a basic document.

Upvotes: 1

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272517

Because 51 is the ASCII value for the character '3'.

Upvotes: 3

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