Cplusplus

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Cplusplus

  1. 1. Introduction to C++<br />Dr. Darren Dancey<br />
  2. 2. Hello World in C++<br />#include &lt;iostream&gt;<br />using namespace std;<br />int main()<br />{<br />cout &lt;&lt; &quot;Hello World!&quot; &lt;&lt; endl;<br />}<br />C++<br />
  3. 3. Hello World in Java<br />import java.io.*;<br />public class Helloworld<br />{<br /> public static void main(Stringargs[])<br /> {<br />System.out.println(&quot;Hello World!&quot;);<br /> }<br />}<br />Java<br />
  4. 4. Much is the same…<br />C++<br />#include&lt;iostream&gt;<br /> <br />usingnamespace std;<br /> <br />intmain(char* args[], intargc)<br />{<br />for(inti = 2; i &lt; 100; i++){<br />bool flag = true; <br />for (intj = 2; j &lt;= i/2; j++ ){<br />if (i%j == 0){<br /> flag = false;<br />break;<br /> }<br /> }<br />if (flag == true){<br />cout &lt;&lt; i &lt;&lt; endl;<br /> }<br /> }<br />cin.get();<br /> <br />}<br />
  5. 5. ...java<br />Java<br />public class week1{<br />public static void main(Stringargs[])<br />{<br />for(inti = 2; i &lt; 100; i++){<br />booleanflag = true; <br /> for (intj = 2; j &lt;= i/2; j++ ){<br /> if (i%j == 0){<br /> flag = false;<br /> break;<br /> }<br /> }<br /> if (flag == true){<br />System.out.println(i);<br /> }<br /> }<br />}<br />}<br />
  6. 6. Compiling a C++ Program <br />C:Usersdarren&gt;cd %HOMEPATH%<br />C:Usersdarren&gt;notepad helloworld.cpp<br />C:Usersdarren&gt;cl /EHschelloworld.cpp<br />Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.762 for 80x86<br />Copyright (C) Microsoft Corporation. All rights reserved.<br />helloworld.cpp<br />Microsoft (R) Incremental Linker Version 8.00.50727.762<br />Copyright (C) Microsoft Corporation. All rights reserved.<br />/out:helloworld.exe<br />helloworld.obj<br />C:Usersdarren&gt;helloworld<br />Hello, World!<br />C:Usersdarren&gt;<br />
  7. 7. Input and Output in C++<br />Input and Output handled by a library<br />I/O part of the C++ Standard Library<br />Stream Based I/O<br />Stream Based Abstraction provides a common interface to I/O for harddisks, terminals, keyboards and the network <br />
  8. 8. The coutObject<br />Instance of type ostream<br />Defined in Standard Library<br />Bound to Console (screen)<br />Character Output Stream<br />Uses Operator overloading of &lt;&lt; (left bit shift) to take arguments to print<br />Similar to <br />cout &lt;&lt; &quot;Hello World!”<br />cout.writeline(“Hello World”) <br />
  9. 9. cout Examples<br />cout &lt;&lt; “Hello, World!”;<br />cout &lt;&lt; 5;<br />cout &lt;&lt; 5.1;<br />intmyvar = 5 <br />cout &lt;&lt; myvar;<br />string course = “SE5301”;<br />cout &lt;&lt; course;<br />cout &lt;&lt; course &lt;&lt; “ is a “ &lt;&lt; 5 &lt;&lt; “star course”; <br />
  10. 10. endl End Line<br />Putting endl onto a stream moves to the next line.<br />cout &lt;&lt; “This is on line 1” &lt;&lt; endl;<br />cout &lt;&lt; “This is on line 2” &lt;&lt; endl;<br />
  11. 11. cin<br />Part of Standard Libaray<br />Instance of istream<br />Bound to the keyboard<br />The &gt;&gt; operator is overridden to provide input method<br />char mychar;<br />cin &gt;&gt; mychar;<br />
  12. 12. cin examples<br /> char mychar;<br />cin &gt;&gt; mychar;<br />intmyint;<br />cin &gt;&gt; myint;<br /> string mystr;<br />cin &gt;&gt; mystr;<br />
  13. 13. I/O Example<br />int age;<br /> <br />cout &lt;&lt; &quot;Please enter you age &quot;;<br />cin &gt;&gt; age;<br /> <br /> <br />if (age &lt; 18){<br />cout &lt;&lt; &quot;Being &quot; &lt;&lt; age;<br />cout &lt;&lt; &quot; years old you are too young to vote&quot; &lt;&lt; endl;<br /> }else{<br />cout &lt;&lt; &quot;You are old enough to vote&quot; &lt;&lt; endl;<br /> }<br />cout &lt;&lt; &quot;Thank you for using vote-o-matic&quot; &lt;&lt; endl;<br />
  14. 14. Pointers<br />
  15. 15. Pointers<br />int myvar1= 5;<br />int myvar2 = 10;<br />double mydbl = 5.3;<br />myvar1<br />myvar2<br />mydbl<br />5<br />1<br />5.3<br />
  16. 16. Pointers<br />int myvar1= 5;<br />int myvar2 = 10;<br />double mydbl = 5.3;<br />int* ptrVar;<br />ptrVar = &myvar2;<br />cout &lt;&lt; *ptrVar ; // will print out 10 (value in myvar2)<br />myvar1<br />myvar2<br />mydbl<br />ptrVar<br />5<br />10<br />5.3<br />Address<br />Of myvar2<br />
  17. 17. Pointers<br />int myvar1= 5;<br />int myvar2 = 10;<br />double mydbl = 5.3;<br />int* ptrVar ;<br />ptrVar = &myvar2;<br />*ptrVar = 20; <br />cout &lt;&lt; myvar2; <br />myvar1<br />myvar2<br />mydbl<br />ptrVar<br />myvar2<br />5<br />10<br />5.3<br />Address<br />Of myvar2<br />20<br />
  18. 18. Arrays in C++<br />int myarray[5] = {10, 20, 30, 50, 5};<br /> for (inti =0 ; i &lt; 5; i++){<br />cout &lt;&lt; myarray[i] &lt;&lt; &quot; &quot; ;<br /> }<br />cin.get();<br />File:SimpleArrayTraversal<br />
  19. 19. Pointer Arithmetic<br />int myarray[5] = {10, 20, 30, 50, 5};<br />int *ptr;<br />ptr = &myarray[0];<br />cout &lt;&lt; &quot;The value of *ptr is &quot; &lt;&lt; *ptr &lt;&lt; endl;<br />cout &lt;&lt; &quot;The value of *(ptr+2) is &quot; &lt;&lt; *(ptr+2) &lt;&lt; endl;<br />cout &lt;&lt; &quot;Array traversal with ptr&quot; &lt;&lt; endl;<br /> for (inti = 0; i &lt; 5; i++){<br />cout &lt;&lt; *(ptr+i) &lt;&lt; endl;<br /> }<br />cout &lt;&lt; &quot;Array Traversal with moving ptr&quot; &lt;&lt; endl;<br /> for (inti = 0; i &lt; 5; i++){ <br />cout &lt;&lt; *ptr++ &lt;&lt; endl;<br /> }<br />File:pointer Arithmetic<br />
  20. 20. C/C++ can be terse<br />while(*ptrString2++ = *ptrString1++);<br />
  21. 21. Pointers<br />Pointers are variables that hold a memory address<br />The * operator get the value in the memory address <br />*ptr get the value stored at the memory address in ptr.<br />The & gets the memory address of a variable<br />ptr = &myvar get the memory address of myvar and stores it in ptr<br />
  22. 22. Pointers and Pass by Reference<br />C++ uses pass by value that means the parameters of a function are copies of the variables passed in.<br />void myfunc (intfoo, int bar)<br />{…}<br />Myfunc(a,b);<br />The values in a and b are copied into foo and bar.<br />
  23. 23. Why By Reference<br />Want to avoid copying large amounts of data.<br />Want the function to modify the value passed in.<br />
  24. 24. Pointers as a Solution<br />Myfunc (int *foo, int *bar){ …}<br />Myfunc(&a, &b)<br />Still pass-by-value but pass in the value of the memory addresses of a and b.<br />When the values pointed to by foo and bar are changed it will be changing a and b.<br />
  25. 25. Objects in C++<br />Dog<br />age: Integer<br />speak()<br />walk( location ) :string<br />
  26. 26. Dog the .h file<br />class dog<br />{<br />public:<br />int age;<br /> char* speak();<br />moveTo(intx, inty);<br />};<br />C++<br />
  27. 27. Dog the .cpp file<br />#include &quot;dog.h&quot;<br />#include &lt;iostream&gt;<br />using namespace std;<br />void Dog::speak()<br />{<br />cout &lt;&lt; &quot;Woof Woof!&quot; &lt;&lt; endl;<br />}<br />C++<br />
  28. 28. Initializing a Dog <br />C++<br />#include &lt;iostream&gt;<br />#include &quot;dog.h&quot;<br />using namespace std;<br />intmain(char* args[], intargc){<br />cout &lt;&lt; &quot;Dog Program&quot; &lt;&lt; endl;<br /> Dog fido; //on stack<br /> //intmyint<br />fido.age = 5;<br />fido.speak();<br />cin.get();<br />}<br />
  29. 29. Scooby a Dynamic Dog <br />C++<br />Dog* scooby = new Dog();<br />(*scooby).speak(); // these calls do<br />scooby-&gt;speak(); //the same thing<br />scooby-&gt;age = 6;<br />
  30. 30. Objects and Pointers<br />int myvar1= 5;<br />int myvar2 = 1;<br />double mydbl = 5.3;<br />myvar1<br />myvar2<br />mydbl<br />5<br />1<br />5.3<br />
  31. 31. Pointers<br />int myvar1= 5;<br />int myvar2 = 1;<br />double mydbl = 5.3;<br />Dog* scooby = new Dog();<br />scooby-&gt;age = 5; <br />myvar1<br />myvar2<br />mydbl<br />scooby<br />age<br />5<br />1<br />5.3<br />Memory<br />address<br />5<br />
  32. 32. CallStackvs Heap<br />Code example callStackExample<br />
  33. 33. Directed Study/Further Reading<br />C++ Pointers <br />http://www.cplusplus.com/doc/tutorial/pointers/<br />Binky Video<br />http://www.docm.mmu.ac.uk/STAFF/D.Dancey/2008/11/25/fun-with-pointers/<br />http://cslibrary.stanford.edu/104/<br />

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