Learn Programming and Web Development with IdiotsDiary

Suppose you want to store the 10 numbers. The one choice is to create a 10 different variable but it is difficult when number of variable are increases. So the next solution that is more feasible is array. An array is the collection of various similar type elements stored in contiguous memory locations. All the array elements share the common name. To uniquely identify each element an index or subscript is associated with the element. so the array is also known as subscript variable . In the given figure arrangement of array elements are shown. The address of the first element is 100. If the given array is of type integer and integer occupies 2 bytes then the next element in the array has address 102,104 etc as given in the figure. How to access array elements using subscript operator it is also shown in the given figure. Array index always start with 0. To access array element subscript operator is used.[] is called subscript operator.a[0] read a of 0 or 0th element of a C...

What is identifier. A Name in Java program is called identifier, which can be used for identification purpose. It can be a class name, interface name, method name, label name, variable name etc. Example In the above example words marked with red underline are identifiers. As you can see there are 5 identifiers Test (Class Name) main (Method Name) String (Pre-defined Class Name) args (Variable Name) println(Method Name) Rules / Convention for Identifier Naming While defining Java identifier name, we have to follow some rules as listed below. Allowed characters in Java identifier are listed below.  A to Z (Uppercase letters) a to z (Lowercase letters) 0 to 9 (Digits) _ (Underscore) $ (Dollar sign) Example:  contact_number ( ✓ ) contact#   (✕) Identifier can't starts with digit. Example abc123 ( ✓ ) 123abc (✕) Java is a case sensitive language all variable listed below are different, but it is not a good pr...

What is Element? An element is the combination of opening tag, closing tag and text between the opening and closing tag. The following figure helps you to understand, what is an element? Element in Html Types of Element in HTML Block level elements Inline elements Block level Element Block Level elements are those which always starts from a new line. Examples of block level elements All Headings (h1,  h2,  h3,  h4, h5, h6) Paragraphs Lists Inline Element Inline elements are those, which don’t change the line automatically. Examples of inline element Bold (<b>Bold</b>) Italic (<i>Italic</i>)  Underline (<i>Underline</i>) Links (<a>Links</a>) Watch the video

Rules for Creating the variable name Variable name can contain Alphabets (A-Z/a-z), Digits (0-9) and Underscore( _ ). A variable name must start with alphabet or underscore. Spaces and special systems are not allowed. Reserved words are not allowed as a variable name. A variable name should be meaningful. Go is case sensitive language so age, Age, AGE all are treated as a different variable. Some correct variable names name father_name fatherName __AGE number1 car_modal_name is_verified intnum Some incorrect variable names father's_name father#name 2persons 0007 000Name int a#b Note There are two popular ways to create multi-word variables. player_name: Each word is separated by an underscore playerName: camel case, the first word is in small and from second word first letter of each word is capitalized. Variable Scope Scope is the range of places where a variable is allowed to be used is called variable scope.Variable Scope can ...

What is Reserved Words. In every language some words are already reserved to represent some action or meaning. For example in English some reserve words are listed below. Apple Run Cat Dog Eat Similarly in Java there are some words which meaning is already reserved, such words are called reserved words / keywords. In Java, Only 53 words are reserved words. Difference between Keywords and Reserved Literals If reserve words represents some functionality, then called Keywords . If reserve words represents some value, the called Reserve Literals . Reserve Literals (3) true (boolean value) false (boolean value) null (Object reference value) Keywords (50) Used Keywords (48) Unused Keyword (2) Goto Const All 53 Reserved Words List Data types (8) byte short int long float double boolean char Flow Control (11) if else switch case default while for do break continue return Modifiers (11) public private pr...

Pointer is called the soul of c. The importance of pointer can be understood by the fact that most of the device driver or embedded system program are created in c. Pointer makes the c most usable and flexible programming. Due to the availability of the pointer, it is possible to write a program such as a device driver. These programs are also known as the device driver. To understand the pointer we have to first understand the memory organization of any variable. The following figure shows the fact. Whenever a variable stored in memory it occupies some memory space and every memory space has a unique number associated with it known as an address. Every byte in member has a different address. If we create an integer variable and suppose it occupy 2 bytes in memory, then two addresses are associated with it but its first address is enough to access it. so the address of next bytes is less useful. To access the address of a variable & (Address of) operator is used. To understa...

Literals in Java int a = 5; In the above expression, a is a variable but 5 is literal. Literal can be of many types, we will discuss all types of literal one by one. Integral Literal Any integer constant is treated as integral literal. it can be written in 3 formats. int a = 10; (decimal format) int a = 010; (octal format, equivalent to 8) int a = 0x10; (hexadecimal format, equivalent to 16) Note: Octal constants can contain digits from 0 to 9. Hexadecimal constants can contains digits from 0 to 9 and a to f, where a to f can be uppercase or lowercase. Example - 1: int a = 10;    ( ✓ ) int a = 0678;    (✕) // Compile time error, number too large int a = 0777;   ( ✓ ) int a = 0xace;   ( ✓ ) int a = 0xBeer;    (✕) // Compile time error, number too large Example - 2: int a; a = 10 + 010 + 0x10; System.out.println(a); // 34, because 010 = 8 and 0x10 = 16 so 10 + 8 + 16 Important Notes We(pr...

What is variable Variable is an entity which can change during the problem. For example: y = x + 5 x y 1 6 2 7 3 8 As shown in the above example, as the value of x is changing y gets changed. so in the above expression x and y are variable and 5 is a constant. In programming whenever you create a variable, a memory is reserved and a name is assigned to it. If initialized with value then binary value of that will gets stored in memory otherwise initialized with default value. Following figure shows the memory map of a variable. Creating a variable var name string = "Hello Go" In the above example, a variable is created labeled with the name of type string and initialized with value "Hello Go" . the var keyword is used to create a variable. var name = "Hello Go"  In the above code snippet, the only difference is that data type is not given, because when you initialize the variable then ...

What is Data type In Java every variable have some type.  For example in the code snippet below x should be int and b should be boolean type variable. x = 10; b = true; Similarly in Java every expression also have some type. For example in the following code snippet if a + b + c would result int type result because a, b and c are int type variables. int a, b, c, d; a = 1; b = 1; c = 1; d  = a + b + c; Strictly type checking  In Java, each type is strictly defined means byte have range from -128 to 127, so value out of from this range is not acceptable by byte type. Each assignment is strictly checked for type compatibility. Due to above two reason java is called strongly type checked language.   Primitive Data Types 8 Primitive Data types in Java Signed / Unsigned Data types Examples int a = 10;  ( ✓ ) int a = -10;  ( ✓ ) float x = -5.8;  ( ✓ ) char ch = -'a';  (✕) boolean b = -true;  (✕) bool...

Introduction of loop Looping is a way to repeat a block of statement for the finite number of times. Here finite means that a loop should be terminated automatically or whenever the user wants. We also learn that a program is a collection of instruction. In C there are various control instructions that control the way to execute the program. Sequence control instruction: In which the program statements are executes in the order in which they are written. Decision making control instruction: In which we make a choice by using the if-else construct. Switch/case control instruction: Alternate choice of if-else construct. Loop control instruction: Used to perform the task repeatedly. We have already learned first 3 control instruction, and now we are going to discuss the last one loop control instruction. Let's start the discussion with an example. Suppose you want to print "Hello", then you write print("Hello"); once. But if I tell you, print ...