read a file upto certain character

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joy 2013-1-15

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采纳的回答： tusu

Hello I have a file which contains 1342400 bits means 10101010010......like this way,

I need to read this file upto 1341440 bits ,how to do so?

after this I need to take chunk of 8bit from this bit sequence and have to convert it in decimal value,separated by ,

like 11111111111111111111111.... i need to convert it in 255,255,255 this way

any help for my two queries

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José-Luis 2013-1-15

编辑：José-Luis 2013-1-15

fread will do that for you. You could read your data as uint8, and avoid transforming between binary and decimal. Is this homework?

joy 2013-1-15

can u give some commands so that i can understand how fread works in certain way

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tusu 2013-1-16

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Joy

 What u can do is...say ur given data set is in a file name test.txt where it has 26 characters..

do the following

txt=filered(test.txt);% now txt variable has all ur 26 chars,but u need first 16
so
new_txt=txt(1:16);

simple

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Image Analyst 2013-1-15

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fread() can do that for a binary file. Is it a binary file or a text file?

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joy 2013-1-15

its a tex file with .txt extension

Image Analyst 2013-1-15

Use fgetl() to get a line of text. Then use bin2dec() to turn a chunk of that text into a number.

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José-Luis 2013-1-15

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The documentation has examples that illustrate how fread() works. Here is a (rather pointless) example of how to read a file bit by bit and then transforming those bits into uint8, which is what you are trying to achieve, if I understood your question right. I insist that it is much better to read directly as uint8

fid = fopen('your_file.txt','r'); 
numBits = 800; %multiple of 8, in this case it means the first 100 characters
your_vals = reshape(fread(fid,800,'ubit1'),[],8);
fclose(fid);
your_ascii_number = sum(bsxfun(@times,your_vals,2.^(7:-1:0)),2);