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<p>Implementation to check whether a number is a power of 2 or not.
<a href="#details">More...</a></p>
<div class="textblock"><code>#include &lt;iostream&gt;</code><br />
<code>#include &lt;cassert&gt;</code><br />
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Include dependency graph for power_of_two.cpp:</div>
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Functions</h2></td></tr>
<tr class="memitem:a8a48be4d7f14e34c5c92925bc1cbf3bb" id="r_a8a48be4d7f14e34c5c92925bc1cbf3bb"><td class="memItemLeft" align="right" valign="top">int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a> (int n)</td></tr>
<tr class="memdesc:a8a48be4d7f14e34c5c92925bc1cbf3bb"><td class="mdescLeft">&#160;</td><td class="mdescRight">This function finds whether a number is power of 2 or not. <br /></td></tr>
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<tr class="memdesc:aa8dca7b867074164d5f45b0f3851269d"><td class="mdescLeft">&#160;</td><td class="mdescRight">Self-test implementations. <br /></td></tr>
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<tr class="memitem:adfd6be45be425ae28c62ce3bfb4b40dc" id="r_adfd6be45be425ae28c62ce3bfb4b40dc"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="#adfd6be45be425ae28c62ce3bfb4b40dc">user_input_test</a> ()</td></tr>
<tr class="memdesc:adfd6be45be425ae28c62ce3bfb4b40dc"><td class="mdescLeft">&#160;</td><td class="mdescRight">Take user input in the test cases (optional; currently commented) <br /></td></tr>
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<tr class="memdesc:ae66f6b31b5ad750f1fe042a706a4e3d4"><td class="mdescLeft">&#160;</td><td class="mdescRight">Main function. <br /></td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Implementation to check whether a number is a power of 2 or not. </p>
<p>This algorithm uses bit manipulation to check if a number is a power of 2 or not.</p>
<h3><a class="anchor" id="autotoc_md86"></a>
Algorithm</h3>
<p>Let the input number be n, then the bitwise and between n and n-1 will let us know whether the number is power of 2 or not</p>
<p>For Example, If N= 32 then N-1 is 31, if we perform bitwise and of these two numbers then the result will be zero, which indicates that it is the power of 2 If N=23 then N-1 is 22, if we perform bitwise and of these two numbers then the result will not be zero , which indicates that it is not the power of 2 </p><dl class="section note"><dt>Note</dt><dd>This implementation is better than naive recursive or iterative approach.</dd></dl>
<dl class="section author"><dt>Author</dt><dd><a href="https://github.com/neha-hasija17" target="_blank">Neha Hasija</a> </dd>
<dd>
<a href="https://github.com/Rijul24" target="_blank">Rijul.S</a> </dd></dl>
</div><h2 class="groupheader">Function Documentation</h2>
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<h2 class="memtitle"><span class="permalink"><a href="#ae66f6b31b5ad750f1fe042a706a4e3d4">&#9670;&#160;</a></span>main()</h2>
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<td class="memname">int main </td>
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<p>Main function. </p>
<dl class="section return"><dt>Returns</dt><dd>0 on exit </dd></dl>
<div class="fragment"><div class="line"><span class="lineno"> 99</span> {</div>
<div class="line"><span class="lineno"> 100</span> <a class="code hl_function" href="#aa8dca7b867074164d5f45b0f3851269d">test</a>(); <span class="comment">// run self-test implementations</span></div>
<div class="line"><span class="lineno"> 101</span> </div>
<div class="line"><span class="lineno"> 102</span> <span class="comment">// uncomment the line below to take user inputs</span></div>
<div class="line"><span class="lineno"> 103</span> <span class="comment">//user_input_test();</span></div>
<div class="line"><span class="lineno"> 104</span> </div>
<div class="line"><span class="lineno"> 105</span> <span class="keywordflow">return</span> 0;</div>
<div class="line"><span class="lineno"> 106</span>}</div>
<div class="ttc" id="apower__of__two_8cpp_html_aa8dca7b867074164d5f45b0f3851269d"><div class="ttname"><a href="#aa8dca7b867074164d5f45b0f3851269d">test</a></div><div class="ttdeci">static void test()</div><div class="ttdoc">Self-test implementations.</div><div class="ttdef"><b>Definition</b> power_of_two.cpp:59</div></div>
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<h2 class="memtitle"><span class="permalink"><a href="#aa8dca7b867074164d5f45b0f3851269d">&#9670;&#160;</a></span>test()</h2>
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<td class="memname">static void test </td>
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<p>Self-test implementations. </p>
<dl class="section return"><dt>Returns</dt><dd>void </dd></dl>
<div class="fragment"><div class="line"><span class="lineno"> 59</span> {</div>
<div class="line"><span class="lineno"> 60</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;First case testing... \n&quot;</span>; <span class="comment">// for n = 32 return 1</span></div>
<div class="line"><span class="lineno"> 61</span> assert(<a class="code hl_function" href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a>(32) == 1);</div>
<div class="line"><span class="lineno"> 62</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;\nPassed!\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 63</span> </div>
<div class="line"><span class="lineno"> 64</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;Second case testing... \n&quot;</span>; <span class="comment">// for n = 5 return 0</span></div>
<div class="line"><span class="lineno"> 65</span> assert(<a class="code hl_function" href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a>(5) == 0);</div>
<div class="line"><span class="lineno"> 66</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;\nPassed!\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 67</span> </div>
<div class="line"><span class="lineno"> 68</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;Third case testing... \n&quot;</span>; <span class="comment">// for n = 232 return 0</span></div>
<div class="line"><span class="lineno"> 69</span> assert(<a class="code hl_function" href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a>(232) == 0);</div>
<div class="line"><span class="lineno"> 70</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;\nPassed!\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 71</span> </div>
<div class="line"><span class="lineno"> 72</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;\nAll test cases have successfully passed!\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 73</span>}</div>
<div class="ttc" id="abasic_ostream_html"><div class="ttname"><a href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a></div></div>
<div class="ttc" id="anamespacemath_html_a8a48be4d7f14e34c5c92925bc1cbf3bb"><div class="ttname"><a href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a></div><div class="ttdeci">int power_of_two(int n)</div><div class="ttdoc">This function finds whether a number is power of 2 or not.</div><div class="ttdef"><b>Definition</b> power_of_two.cpp:42</div></div>
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<h2 class="memtitle"><span class="permalink"><a href="#adfd6be45be425ae28c62ce3bfb4b40dc">&#9670;&#160;</a></span>user_input_test()</h2>
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<p>Take user input in the test cases (optional; currently commented) </p>
<dl class="section return"><dt>Returns</dt><dd>void </dd></dl>
<p>function call with</p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">n</td><td></td></tr>
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<div class="fragment"><div class="line"><span class="lineno"> 79</span> {</div>
<div class="line"><span class="lineno"> 80</span> <span class="keywordtype">int</span> n = 0; <span class="comment">// input from user</span></div>
<div class="line"><span class="lineno"> 81</span> </div>
<div class="line"><span class="lineno"> 82</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;Enter a number &quot;</span> &lt;&lt; <a class="code hl_functionRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/manip/endl.html">std::endl</a>;</div>
<div class="line"><span class="lineno"> 83</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_istream.html">std::cin</a> &gt;&gt; n; </div>
<div class="line"><span class="lineno"> 84</span><span class="comment"></span> </div>
<div class="line"><span class="lineno"> 85</span><span class="comment"> /// function call with @param n</span></div>
<div class="line"><span class="lineno"> 86</span><span class="comment"></span> <span class="keywordtype">int</span> <a class="code hl_function" href="../../de/dc3/fibonacci__sum_8cpp.html#aadb40ac4c74a7efc0680b83eeee138aa">result</a> = <a class="code hl_function" href="../../dd/d47/namespacemath.html#a8a48be4d7f14e34c5c92925bc1cbf3bb">math::power_of_two</a>(n);</div>
<div class="line"><span class="lineno"> 87</span> <span class="keywordflow">if</span> (result == 1) {</div>
<div class="line"><span class="lineno"> 88</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;Yes, the number &quot;</span> &lt;&lt; n &lt;&lt; <span class="stringliteral">&quot; is a power of 2\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 89</span> }</div>
<div class="line"><span class="lineno"> 90</span> <span class="keywordflow">else</span> { </div>
<div class="line"><span class="lineno"> 91</span> <a class="code hl_classRef" target="_blank" href="http://en.cppreference.com/w/cpp/io/basic_ostream.html">std::cout</a> &lt;&lt; <span class="stringliteral">&quot;No, the number &quot;</span> &lt;&lt; n &lt;&lt; <span class="stringliteral">&quot; is not a power of 2\n&quot;</span>;</div>
<div class="line"><span class="lineno"> 92</span> }</div>
<div class="line"><span class="lineno"> 93</span>}</div>
<div class="ttc" id="abasic_istream_html"><div class="ttname"><a href="http://en.cppreference.com/w/cpp/io/basic_istream.html">std::cin</a></div></div>
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<div class="ttc" id="afibonacci__sum_8cpp_html_aadb40ac4c74a7efc0680b83eeee138aa"><div class="ttname"><a href="../../de/dc3/fibonacci__sum_8cpp.html#aadb40ac4c74a7efc0680b83eeee138aa">math::fibonacci_sum::result</a></div><div class="ttdeci">uint64_t result(uint64_t n)</div><div class="ttdef"><b>Definition</b> fibonacci_sum.cpp:77</div></div>
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