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    <p>Here's the best method I could come up with for setting individual bits of a variable: Assume we need to set the first four bits of variable1 (a char or other byte long variable) to 1010</p> <pre><code>variable1 &amp;= 0b00001111; //Zero the first four bytes variable1 |= 0b10100000; //Set them to 1010, its important that any unaffected bits be zero </code></pre> <p>This could be extended to whatever bits desired by placing zeros in the first number corresponding to the bits which you wish to set (the first four in the example's case), and placing zeros in the second number corresponding to the bits which you wish to remain neutral in the second number (the last four in the example's case). The second number could also be derived by bit-shifting your desired value by the appropriate number of places (which would have been four in the example's case).</p> <p>In response to your comment this can be modified as follows to accommodate for increased variability:</p> <p>For this operation we will need two shifts assuming you wish to be able to modify non-starting and non-ending bits. There are two sets of bits in this case the first (from the left) set of unaffected bits and the second set. If you wish to modify four bits skipping the first bit from the left (1 <em>these four bits</em> 111 for a single byte), the first shift would be would be 7 and the second shift would be 5.</p> <pre><code>variable1 &amp;= ( ( 0b11111111 &lt;&lt; shift1 ) | 0b11111111 &gt;&gt; shift2 ); </code></pre> <p>Next the value we wish to assign needs to be shifted and or'ed in. However, we will need a third shift to account for how many bits we want to set. This shift (we'll call it <code>shift3</code>) is <code>shift1</code> minus the number of bits we wish to modify (as previously mentioned 4).</p> <pre><code>variable1 |= ( value &lt;&lt; shift3 ); </code></pre>
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    1. POString to very long sequence of length less than 1 byte
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    1. COThanks :) There're two problems. First: 0bxxx is invalid prefix for ANSI C/C++ value ;) That's no problem. Problem is that masking value + shift length is not constant. I am asking about a principle how to determine these values and how to write such algorithm in a smart way ;)
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    2. CO@Adam 0b is used by most modern C/C++ compilers as a way to represent binary values. I've edited my answer to include high variability. You can now use this algorithm to edit any amount of bits in the middle of a byte or at the ends. This can be expanded to multiple-byte types (you may have to account for Endianess).
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