c++ for dummys.txt

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     The default 
     installation 
         options 
       should be 
     acceptable 
         to most 
          users. 
                  5. Click the Next button. 
                     The installation program asks where you want it to install Dev-C++, using 
                     a message like that shown in Figure 1-3. 
      Figure 1-3: 
     The default 
     location for 
    the Dev-C++ 
    environment 
     is provided. 
                  6. Accept the default directory, c:\Dev-CPP. 
                     Don’t install Dev-C++ in the directory \Program Files with all the other 
                    executables. That’s because Dev-C++ doesn’t do well with directories that 
                    contain spaces in their names. I haven’t experimented much along these 
                    lines, but I believe you can use any other directory name without any 
                    special characters other than ‘_’. It’s safer just to accept the default. 
                  7. Make sure you have enough room for the program, wherever you 
                     decide to put it. 
                     The Dev-C++ environment uses only a paltry 45MB, but it’s always good 
                     practice to check. 
                  8. Click Install. 
                     At first, nothing seems to happen. Then Dev-C++ gets going, copying a 
                     whole passel of files to the Dev-CPP directory — putting absolutely noth 
                     ing in the Windows home directory. Figure 1-4 displays the eventual result. 
             
 
                                                   Chapter 1: Writing Your First C++ Program      15 
Figure 1-4: 
  The Dev- 
        C++ 
installation 
   process 
  unzips a 
       large 
 number of 
mostly small 
       files. 
                  While the installation is going on, Dev-C++ presents a window that asks 
                  whether you want to install for all users once it’s done copying files onto 
                  your hard drive. That question boils down to this: If someone else logs 
                  on to your computer, do you want her or him to be able to execute Dev- 
                  C++? (The answer is “Yes” in my case.) 
               9. Choose whether you want to install for all users, and then click the 
                  Close button to complete installation of the package. 
                  Dev-C++ starts immediately, so you can set its options properly for your 
                  needs. (Yep, there’s more work to do. But you knew that. Read on.) 
             Setting the options
 
             As you probably know if you’ve spent more than a coffee break’s worth of time 
             installing software, setting options is a procedure unto itself. In this case, Dev- 
             C++ has two options that must be set before you can use it. Set ’em as follows: 
               1. Choose ToolsCompiler Options. 
                  You can change these settings at any time, but now is as good as any. 
               2. Choose the Settings tab. 
               3. Choose Code Generation from the menu on the left. 
                  Make sure that the Enable Exception Handling is enabled, as shown in 
                  Figure 1-5. (If it isn’t, click on the option box to display the two choices 
                  and select Yes.) 
               4. Choose Linker and make sure the Generate Debugging Information 
                  option is enabled. 
                  Figure 1-6 shows you what to look for. 
        
 
16   Part I: Introduction to C++ Programming 
      Figure 1-5: 
     The Enable 
      Exception 
       Handling 
     option must 
     be enabled. 
      Figure 1-6: 
            The 
       Generate 
     Debugging 
     Information 
     option must 
     be enabled. 
                   5. Choose OK. 
                      Installation is now complete! (Your options are saved automatically.) 
  Creating Your First C++ Program 
                 In this section, you create your first C++ program. You first enter the C++ code 
                 into a file called CONVERT.CPP, and then convert the C++ code into an exe 
                 cutable program. 
            
 
                                    Chapter 1: Writing Your First C++ Program       17 
  Entering the C++ code
 
  The first step to creating any C++ program is to enter C++ instructions using a 
  text editor. The Dev-C++ user interface is built around a program editor specifi 
  cally designed to create C++ programs. 
    1. Click StartProgramsBloodshed Dev-C++Dev-C++ to start up the 
       Dev-C++ tool. 
       The Dev-C++ interface looks fundamentally like that of any other Win 
       dows program — perhaps a little clunkier, but a Windows application 
       nonetheless. 
       This is a lot of clicking. My personal preference is to create a shortcut 
       on the desktop. To create a shortcut, double-click My Computer. Now 
       double-click the Local Disk (C:). Finally, double-click Dev-CPP — whew! 
       Right-click the file devcpp.exe and choose Create Shortcut from the 
       drop down menu. Drag the Shortcut to devcpp.exe file onto your 
       desktop (or some other easily accessible place). From now on, you can 
       just double-click the shortcut to start Dev-C++. 
    2. Choose FileNewSource File. 
       Dev-C++ opens a blank window wherein you get to enter your new code. 
       Don’t worry if you find yourself wishing you knew what to enter right 
       now — that’s why you bought this book. 
    3. Enter the following program exactly as written. 
       Don’t worry too much about indentation or spacing — it isn’t critical 
       whether a given line is indented two or three spaces, or whether there 
       are one or two spaces between two words. C++ is case sensitive, how 
       ever, so you need to make sure everything is lowercase. 
       You can cheat and copy the Conversion.cpp file contained on the 
       enclosed CD-ROM in directory \CPP_Programs\Chap01. 
        // 
        // Program to convert temperature from Celsius degree 
        // units into Fahrenheit degree units: 
        // Fahrenheit = Celsius * (212 - 32)/100 + 32 
        // 
        #include <cstdio> 
        #include <cstdlib> 
        #include <iostream> 
        using namespace std; 
        int main(int nNumberofArgs, char* pszArgs[]) 
        { 
    
 
18   Part I: Introduction to C++ Programming 
                         // enter the temperature in Celsius 
                         int celsius; 
                         cout << “Enter the temperature in Celsius:”; 
                         cin >> celsius; 
                         // calculate conversion factor for Celsius 
                         // to Fahrenheit 
                         int factor; 
                         factor = 212 - 32; 
                         // use conversion factor to convert Celsius 
                         // into Fahrenheit values 
                         int fahrenheit; 
                         fahrenheit = factor * celsius/100 + 32; 
                         // output the results (followed by a NewLine) 
                         cout << “Fahrenheit value is:”; 
                         cout << fahrenheit << endl; 
                         // wait until user is ready before terminating program 
                         // to allow the user to see the program results 
                         system(“PAUSE”); 
                         return 0; 
                       } 
                  4. Choose Save As under the File menu. Then type in the program name 
                     and press Enter. 
                     I know that it may not seem all that exciting, but you’ve just created 
                     your first C++ program! 
                     For purposes of this book, I created a folder CPP_Programs. Within this, 
                     I created Chap01. Finally, I saved the program with the name Conversion. 
                     cpp. Note that Dev-C++ won’t work properly with directory names that 
                     contain spaces. (It doesn’t have a problem with names longer than eight 
                     characters in length — thank goodness!) 
                Building your program
 
                After you’ve saved your Conversion.cpp C++ source file to disk, it’s time to 
                generate the executable machine instructions. 
                To build your Conversion.cpp program, you choose ExecuteCompile from 
                the menu or press F9 — or you can even click that cute little icon with four 
                colored squares on the menu bar (use the Tool Tips to see which one I’m talk 
                ing about). In response, Dev-C++ opens a compiling window. Nothing will 
                happen at first (sshh . . . it’s thinking). After a second or two, Dev-C++ seems 
                to take off, compiling your program with gusto. If all goes well, a window like 
                that shown in Figure 1-7 appears. 
           
 
                                              Chapter 1: Writing Your First C++ Program        19 
  Figure 1-7: 
 The user is 
   rewarded 
      with a 
simple Done 
 message if 
his program 
is error free. 
              Dev-C++ generates a message if it finds any type of error in your C++ program — 
              and coding errors are about as common as snow in Alaska. You’ll undoubtedly 
              encounter numerous warnings and error messages, probably even when enter 
              ing the simple Conversion.cpp. To demonstrate the error-reporting process, 
              let’s change Line 17 from cin >> celsius; to cin >>> celsius;. 
              This seems an innocent enough offense — forgivable to you and me perhaps, 
              but not to C++. Dev-C++ opens a Compiler tab, as shown in Figure 1-8. The mes 
              sage parse error before ‘> is perhaps a little terse, but descriptive. To get 
              rid of the message, remove the extra > and recompile. 
  Figure 1-8: 
    Bad little 
   programs 
   generate 
        error 
messages in 
the Compiler 
    window. 
         
 
20   Part I: Introduction to C++ Programming 
                                   Why is C++ so picky?