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Programming and Problem Solving with C++

  <td><font face="Times New Roman, Times, Serif" size="3"><i>Library Functions</i></font></td>
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  <td><font face="Times New Roman, Times, Serif" size="3">Certain computations, such as taking square roots or finding the absolute value of a number, are very common in programs. It would be an enormous waste of time if every programmer had to start from scratch and create functions to perform these tasks. To help make the programmer's life easier, every C++ system includes a <i>standard library</i>-a large collection of prewritten functions that any C++ programmer may use. Here is a very small sample:</font></td>
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<table cellspacing="0" width="672" cellpadding="7"><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Header File</i></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Function</i></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Parameter Type(s)</i></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Result Type</i></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Result</i></font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;stdlib.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">abs(i)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">int</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">int</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Absolute value of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">i</font><font face="Times New Roman, Times, Serif" size="2"></font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;math.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">cos(x)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Cosine of x(x is in radians)</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;math.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">fabs(x)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Absolute value of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">j</font><font face="Times New Roman, Times, Serif" size="2"></font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;stdlib.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">labs(j)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Absolute value of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">j</font><font face="Times New Roman, Times, Serif" size="2"></font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;math.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">pow(x, y)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><table border="0" cellspacing="0" cellpadding="0"><tr><td 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  <td><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"> raised to the power </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">y</font><font face="Times New Roman, Times, Serif" size="2"> (if </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"> = 0.0, </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">y</font><font face="Times New Roman, Times, Serif" size="2"> must be a whole number)</font></td>
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</tr></table></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;math.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">sin(x)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Since of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"> ( </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"> is in radians)</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">&lt;math.h&gt;</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">squrt(x)</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">float</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">Square root of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"> ( </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">x</font><font face="Times New Roman, Times, Serif" size="2"></font><font face="Symbol" size="2">镁</font><font face="Times New Roman, Times, Serif" size="2">0.0)</font></td></tr></table></td></tr></table><br /><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>
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  <td><font face="Times New Roman, Times, Serif" size="3">(Technically, the entries marked </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">float</font><font face="Times New Roman, Times, Serif" size="3"> should all say </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">double</font><font face="Times New Roman, Times, Serif" size="3">. These library functions perform their work using double precision floating point values. But because of type coercion, the functions work just as you would like them to when you </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">pass float</font><font face="Times New Roman, Times, Serif" size="3"> values to them.)</font></td>
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  <td><font face="Times New Roman, Times, Serif" size="3">Using a library function is easy. First, you place an </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">#include</font><font face="Times New Roman, Times, Serif" size="3"> directive near the top of your program, specifying the appropriate header file. This directive ensures that the C++ preprocessor will insert declarations into your program that give the compiler some information about the function. Then,</font></td>
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