Java - Intro to Classes and Objects

If you become part of a development team in industry, you might work on applications that contain hundreds, or even thousands, of classes.




excerpt from "Java how to program, by Deitel" page 73

JAVA - the System class. And, the package java.lang.

System.out.print("Enter first integer: "); //prompt

System is a class. Class System is part of package java.lang. Notice that class System is not imported with an import declaration at the beginning of the program.

**By default, package java.lang is imported in every Java program; thus, classes in java.lang are the only ones in the java API that do not require an import declaration.


excerpted from "Java how to program,by Deitel"

JAVA - Libraries and APIs documentation

Excerpt from "Java How to Program, by Deitel":

For each new Java API class we  use, we indicate the package in which it is located. This information helps you locate descriptions of each package and class in the Java API documentation.

A web version of this documentation can be found at :
java.sun.com/javase/6/docs/api/

You can download this documentation from
java.sun.com/javase/downloads

Appendix E shows how to use this documentation.

C - One way to get input from keyboard

references:
1. Oualline, S. (1997). Practical C Programming, 3rd ed., O'Reilly Media, Inc.
2. BJ Furman | ME 30 Computer Applications | A Better Way to Get Input From the Keyboard.doc

/* Example of a robust way to get input from the keyboard*/
#include <stdio.h>
/*declare variables that you want to read in*/
char char1;
int var1;
float var2;
char string1[20]; /*an array to hold 19 characters*/

char line[100]; /*for the line of user input*/
/*put a user prompt here*/
/*get and process the user input*/

fgets(line, sizeof(line). stdin);
sscanf( line, "%s %c %f %d", string1, &char1, &var2, &var1);


Step-by-Step:
1. Declare variables you want to use to store the input
2. Declare an array of characters that is long enough to contain what the user will enter
         char line[100];
3. Get the line of input and process it to store the variables
         fgets (line, sizeof(line), stdin);
        sscanf (line, "%s %c %f %d", string1, &char1, &var2, &var1);

How Things Work:
1. fgets() gets a line of input (note: 100 characters maximum including the EOL) from stdin (the keyboard)
2. sscanf() (string scanf()) scans the input line string and processes it according to the control string (i.e., the conversion specifications between the double-quotes)
3. sscanf() must have pointers to the variables (hence ampersands in front of the variable names, and the use of a character array (string[20]) in the parameter list )
4. * Of course the conversion specifications in the control string must match the list of variables in order for this to work properly.