Syntax and Semantics, and the Program Development Process ROBERT REAVES

More About Output  Control vertical spacing by using the endl manipulator in an output statement.  What will the following produce?  cout << “Hi There, “ << endl;  cout << endl;  cout << “Lois Lane.” << endl;

 It is possible to do in one line.  cout << “Hi there, “ << endl << endl << “Lois Lane.” << endl;  Another:  cout << “Hi there, “ << endl << endl << “Lois Lane.” << endl;  This is to show we can spread a single C++ statement onto more than one line of the program.  semicolon

Inserting Blanks Within a Line  To control horizontal spacing of output, one technique is to send extra black characters to the output stream.  cout << “* * * * * *” << endl;  Produces:  * * * * * *  These are enclosed in double quotes so they print literally as they are written in the program.  What about:  cout << ‘*’ << ‘*’;

Special Characters  \” allows for quotes within a string sent to the output stream.  \n is a newline character, can use instead of endl.  \\ allows for the use of a \ within a string sent to the output stream.  What does produce?  cout << ‘”’ << “’”;  cout << “\”” << ‘\’’;

Enter Program Compile Program Compile- time Errors? Run Program Success! Logic errors? Go back to algorithm and fix design. No Yes Figure out errors.

Summary  Syntax of the C++ language is defined by metalanguage.  Identifiers are used in C++ to name things, some are called reserved words.  Have predefined meanings in the language.  Identifiers are restricted to those not reserved by the C++ language.  Identifiers are associated with memory locations by declarations.

Summary  Declarations may give a name to a location whose value doesn’t change, constant, and whose do change, variable.  Every constant and variable has a data type.  Common ones:  int  float  char  string, from the standard library

Summary  Program output is accomplished by means of the output stream variable cout, along with the insertion operator (<<).  Sends to the standard output device.  endl manipulator tells the computer to terminate the current output line and go on to the next.  Output should be clear, understandable, and neatly arranged.

Summary  A C++ program is a collection of one or more function definitions.  One of them must be main.  Execution always begins with the main function.  Functions all cooperate to produce the desired results.