I'm A dark horse-----the c-language foundation of iOS development
Last Update:2015-07-01
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<span id="Label3"></p><p><p><strong>C language in the study of the heavy Difficulties:</strong></p></p>1) operator: self-increment, Self-subtraction. 2) into the system: a variety of conversion, the original code, anti-code, and Complement. 3) Arrays: one-dimensional arrays, two-dimensional arrays, multidimensional arrays. 4) loop: Multiple loops nesting, finding, sorting. 5) function: Call of normal function, recursive Function. 6) pointers: first-level pointers, multi-level pointers, array pointers, pointers and arrays, functions, structures, relationships between, 7) memory management: c-language memory management issues, memory leaks, Wild Pointers. 8) have a macro and conditional compilation. 9) multi-file Development<strong><strong>pre-learning c key input and output functions: printf () and scanf ()</strong></strong><strong><strong></strong></strong><strong><strong></strong></strong><strong><strong>the difference between a++ and ++a:</strong></strong>The order of operations is to see where "+ +" is Located. If + + in front, is the first plus 1 and then calculate, if it is "+ +" after the first calculation, plus 1. Practice:<pre><pre><span style="color: #008080;">1</span> <span style="color: #0000ff;">int</span> <span style="color: #0000ff;">int</span> <span style="color: #800080;">5</span> <span style="color: #000000;"></span> <span style="color: #008080;">2</span> b = (++a) + (a++<span style="color: #000000;">);</span> <span style="color: #008080;">3</span> printf (<span style="color: #800000;">"</span><span style="color: #800000;">b=%d, a=%d\n</span><span style="color: #800000;">"</span>, b, a);</pre></pre>Answer:<pre><pre><span style="color: #008080;">1</span> <span style="color: #008000;">/*</span> <span style="color: #008080;">2</span> <span style="color: #008000;">answer:</span> <span style="color: #008080;">3</span> the <span style="color: #008000;">difference between "++a" and "a++" is</span> the subject of the Examination. <span style="color: #008080;">4</span> <span style="color: #008000;">++a is calculated first and then participates in the calculation here: (++a) = 6</span><span style="color: #008080;">5</span><span style="color: #008000;">a++ calculated after the calculation, because just now executed the "++a" so at this time a = 6, (a++) =6</span><span style="color: #008080;">6 </span> <span style="color: #008000;">So B = (++a) + (a++)</span><span style="color: #008080;">7</span><span style="color: #008000;"> b = 6 + 6 b equals</span><span style="color: #008080;">8</span> <span style="color: #008000;">a after 2 + + operations at this time the value is 7</span> <span style="color: #008080;">9</span> <span style="color: #008000;">*/</span></pre></pre><strong><strong>switch case penetration problem:</strong></strong>Case should be used in conjunction with the break keyword, and if it is not added, all of the following will be run by the Computer. Penetrating case:<pre><span style="color: #008080;"><span style="color: #008080;">1</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">Switch</span></span>（<span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">) {</span></span><span style="color: #008080;"><span style="color: #008080;">2</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">3</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">4</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">5</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">6</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">3</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">7</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">3</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">8</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">4</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">9</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">4</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">Ten</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">5</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;"></span> one</span>printf ("<span style="color: #800080;"><span style="color: #800080;">5</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;"></span> a</span> <span style="color: #0000ff;"><span style="color: #0000ff;">default</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span> <span style="color: #800080;"><span style="color: #800080;">0</span></span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span>}</pre>Output result:<pre><pre><span style="color: #008000;">//</span> <span style="color: #008000;">printf ("2");</span> <span style="color: #008000;">//</span> <span style="color: #008000;">printf ("3");</span> <span style="color: #008000;">//</span> <span style="color: #008000;">printf ("4");</span> <span style="color: #008000;">//</span> <span style="color: #008000;">printf ("5");</span> <span style="color: #008000;">//</span> the <span style="color: #008000;">above code will execute! </span>results:<span style="color: #800080;">2345</span></pre></pre>Do not penetrate:<pre><span style="color: #008080;"><span style="color: #008080;">1</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">Switch</span></span>（<span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">) {</span></span><span style="color: #008080;"><span style="color: #008080;">2</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">3</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">4</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> break</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;">5</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">6</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">2</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">7</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> break</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;">8</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">3</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;">9</span></span>printf ("<span style="color: #800080;"><span style="color: #800080;">3</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;">Ten</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> break</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> one</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">4</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;"></span> a</span>printf ("<span style="color: #800080;"><span style="color: #800080;">4</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> break</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> case</span> <span style="color: #800080;"><span style="color: #800080;">5</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;"></span> the</span>printf ("<span style="color: #800080;"><span style="color: #800080;">5</span></span><span style="color: #000000;"><span style="color: #000000;">");</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> break</span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;">default</span></span><span style="color: #000000;"><span style="color: #000000;">:</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span> <span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span> <span style="color: #800080;"><span style="color: #800080;">0</span></span><span style="color: #000000;"><span style="color: #000000;">;</span></span><span style="color: #008080;"><span style="color: #008080;"></span> +</span>}</pre>Output result:<span class="cnblogs_code"><span class="cnblogs_code"> <span style="color: #008080;">1</span> <span style="color: #008000;">//</span><span style="color: #008000;">printf ("2");</span> <span style="color: #008080;">2</span> results:<span style="color: #800080;">2</span> </span></span><strong><strong>cyclic conditions in each of the C languages:</strong></strong><pre><pre><span style="color: #008080;">1</span> <span style="color: #0000ff;"></span>for (;<span style="color: #0000ff;">true</span><span style="color: #000000;">;) {}</span><span style="color: #008080;">2</span><span style="color: #0000ff;"></span>while (<span style="color: #0000ff;">true</span><span style="color: #000000;">)</span><span style="color: #008080;">3</span> <span style="color: #0000ff;"></span> do .... <span style="color: #0000ff;"></span>while (<span style="color: #0000ff;">true</span><span style="color: #008000;">//</span> in <span style="color: #008000;">any case, it loops once.) </span></pre></pre>Loops are entered only when the parentheses are "true". All languages are the Same. Bubble sort for the for loop app: there are two sorts: 1, large number sinking 2, fractional floating difference is only the "<" ">" in the for Loop. Code implementation:<pre><span style="color: #008080;"><span style="color: #008080;">1</span></span>#include <stdio.h><span style="color: #008080;"><span style="color: #008080;">2</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span>Maopao (<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span>arr[],<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span><span style="color: #000000;"><span style="color: #000000;">Len) {</span></span><span style="color: #008080;"><span style="color: #008080;">3</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span><span style="color: #000000;"><span style="color: #000000;">temp; </span></span><span style="color: #008080;"><span style="color: #008080;">4</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> for</span>(<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span>j =<span style="color: #800080;"><span style="color: #800080;">0</span></span>; j<len-<span style="color: #800080;"><span style="color: #800080;">1</span></span>-i;j++<span style="color: #000000;"><span style="color: #000000;">){</span></span><span style="color: #008080;"><span style="color: #008080;">5</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(arr[i]>arr[j+<span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">]) {</span></span><span style="color: #008080;"><span style="color: #008080;">6</span></span>temp =<span style="color: #000000;"><span style="color: #000000;">arr[i];</span></span><span style="color: #008080;"><span style="color: #008080;">7</span></span>arr[j] = arr[j+<span style="color: #800080;"><span style="color: #800080;">1</span></span><span style="color: #000000;"><span style="color: #000000;">];</span></span><span style="color: #008080;"><span style="color: #008080;">8</span></span>arr[j+<span style="color: #800080;"><span style="color: #800080;">1</span></span>] =<span style="color: #000000;"><span style="color: #000000;">temp;</span></span><span style="color: #008080;"><span style="color: #008080;">9</span></span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;">Ten</span></span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> one</span>}</pre>Select sort for loop app: code implementation:<pre><span style="color: #008080;"><span style="color: #008080;">1</span></span>#include <stdio.h><span style="color: #008080;"><span style="color: #008080;">2</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span>Selectsor (<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span>arr[],<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span><span style="color: #000000;"><span style="color: #000000;">Len) {</span></span><span style="color: #008080;"><span style="color: #008080;">3</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span><span style="color: #000000;"><span style="color: #000000;">temp;</span></span><span style="color: #008080;"><span style="color: #008080;">4</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> for</span>(<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span>i =<span style="color: #800080;"><span style="color: #800080;">0</span></span>; i<len-<span style="color: #800080;"><span style="color: #800080;">1</span></span>; i++<span style="color: #000000;"><span style="color: #000000;">){</span></span><span style="color: #008080;"><span style="color: #008080;">5</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;"></span> for</span>(<span style="color: #0000ff;"><span style="color: #0000ff;">int</span></span>j = i +<span style="color: #800080;"><span style="color: #800080;">1</span></span>; j<len;j++<span style="color: #000000;"><span style="color: #000000;">){</span></span><span style="color: #008080;"><span style="color: #008080;">6</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(arr[i] ><span style="color: #000000;"><span style="color: #000000;">Arr[j]) {</span></span><span style="color: #008080;"><span style="color: #008080;">7</span></span>temp =<span style="color: #000000;"><span style="color: #000000;">arr[i];</span></span><span style="color: #008080;"><span style="color: #008080;">8</span></span>arr[i] =<span style="color: #000000;"><span style="color: #000000;">arr[j];</span></span><span style="color: #008080;"><span style="color: #008080;">9</span></span>arr[j] =<span style="color: #000000;"><span style="color: #000000;">temp;</span></span><span style="color: #008080;"><span style="color: #008080;">Ten</span></span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> one</span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> a</span> <span style="color: #000000;"><span style="color: #000000;"> }</span></span><span style="color: #008080;"><span style="color: #008080;"></span> -</span>}</pre><p><p></p></p><p><p>I'm A dark horse-----the c-language foundation of iOS development</p></p></span>
