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JSON Tutorial Basic to Advance

JSON stand for Java Script Object Notation (JSON).

JSON is not a Programming Language. JSON is a data interchange format.

Using JSON we can transfer data between client and server and server to server.

JSON is defined in RFC4627 written in 2006. Internet Engineering Task Force (IETF) published JSON RFC7159 in March 2014.

Later on standard updated on RFC8259 and EMCA 404

JSON media type(MIME type) is application/json

JSON file extension is <code>.json</code>

In JSON data can be in following structure

  • A collection of name/value pair
  • An ordered list of value

These two are the universal data structure supported by approx all programming languages. So data exchange between one language to another is easy by JSON.

JSON string example is as below

Why use JSON?

As JSON format is text only, it can be sent to server and also can received from a server, and also can be used as a data format by any programming language.

If you receive data from a server, in JSON format, you can use it like any other JS object.

JSON Syntax

JSON syntax is derived from JS object notation syntax.

•        Data is in name/value pairs

•        Curly braces hold objects

•        Data is separated by commas

•        Square brackets hold arrays

JSON Data

JSON data is written as name or value pairs.

A name or value pair consists of a field name like this “”, and it will follow by a colon, and also followed by a value:

Example

{“name”:”Ayan” }

JSON – Evaluates to JS Objects

The JSON format is a also JavaScript objects.

In JSON, keys must be strings, written with double quotes:

JSON

{ “name”:”Ayan” }

In JSON, keys can be strings, numbers, or identifier names,

{ name:”Ayan” }

JSON with JavaScript Syntax

JSON syntax is derived from JavaScript object notation, very little extra software is needed to work with JSON within JS.

With JS you can create an object and assign data to it.

Example

Access a JavaScript object

Result

Ayan

produce the same output as above

JSON Values

In JSON, values must be one of the following data types:

  •   a string 
  •   a number
  • an object
  •   an array

or one of the following literal names

  • false
  • true
  • null
JSON Value
Fig : JSON Value

JSON String Value

String value is represented in quotation any unicode character is used to create string.

like

” ” //empty string
“Ram” //string value
“\”” // use of escape character
“\uXXXX” // unicode value

JSON Numbers

 JSON allows numbers as an integer or a floating point numbers.

Example

25
24.25
3.55
3.1e3

JSON Objects

Values in JSON can be objects. It contains zero or more name value pairs in curly braces seperated by comma

Example

{
“employee”:{ “name”:”Ayan”, “age”:25, “city”:”Mumbai” }
}

JSON Array

JSON Array are surrounded by [ (squrae bracket) and zero or more values or elements are seperated by comma.

The values in array may be of different types.

Example

[“red’,”blue”,”green”, “orange”]

A composite JSON structure is also possible

Here a JSON array contains two objects and each object contains string, number and array values

JSON is purely a data format — it contains only properties, no methods.

  • JSON need a double quotes to be used around strings and property names. Single quotes are not valid in a JSON.
  • A single misplaced colon or comma can cause a JSON file to go wrong, and not working that JSON file. Always be careful to validate any data in JSON. A validate JSON using an application like JSONLint.
  •    JSON can be taken the form of any data type that is valid for inside JSON, not just arrays or objects. So, a single string or a number can be a valid JSON object.
  • Unlike in JavaScript code in which object properties may be unquoted, in JSON, only quoted strings may be used as properties.

Converting between objects and textSection

In JSON can be set the XHR request to convert the JSON response directly into a JS object using:

request.responseType = ‘json’;

But sometimes can be receive a raw JSON string, and  need to convert it to an object.

when try to send a JavaScript object across the network, then need to convert it to JSON (a string) before sending.

These two problems are so common that a built-in JSON object is available, which contains the following two methods:

  • parse(): Accepts a JSON string as a parameter, and returns the corresponding JavaScript object.
  • stringify(): Accepts an object as a parameter, and returns the equivalent JSON string form.

See one example of stringify()

{“name”:”Ram”,”age”:24,”mailIds”:[“[email protected]”,”[email protected]”,”[email protected]”]}

console.table(obj); prints array in tabular format
console.log(obj[0].name); print first objects name
for (var row in obj) will iterate each object and access its properties in name value pair

Example

Sam Ghosh

JSON.parse()

A common use of JSON is to exchange data to/from a web server.

parse() is used to convert JSON data to JavaScript values

Server send data as a string. To convert this string to JavaScript object  JSON.parse() method is used

Example – Parsing JSON

This text received from a web server:

‘{ “name”:”Ayan”, “age”:25, “city”:”Mumbai”}’

Use the JavaScript function JSON.parse() to convert text into a JavaScript object:

varobj = JSON.parse(‘{ “name”:”Ayan”, “age”:25, “city”:”Mumbai”}’);

Use the JavaScript function JSON.parse() to convert text into a JavaScript object:

Example

Create Object from JSON String

Ayan, 25

How to access nested JSON objects

Bajaj Bajaj

JSON Arrays

EXAMPLE

Access an array value of a JSON object

Honda

EXAMPLE

Looping through an array using a for in loop

Honda Bajaj Hero

EXAMPLE

Looping through arrays inside arrays

Nested JSON Objects

Honda Hornet xblade livo Bajaj pulsar neon X5 Hero 500 Panda

See one Example to read JSON data and show in console

Result

Console.table()
Fig: Console.table()

JSON Vs XML

Extensible Markup Language(XML) is a Markup Language.

XML is used to access and transfer the data same like JSON.

XML uses tag to wrap content.

General structure of XML to send send data is as below

For above data JSON is

XML and JSON both are data interchange format.

In XML we have to add additional tags to carry data that is not is JSON no overhead required to carry data in JSON

JSON is based on JavaScript. XML is derived from SGML.

JSON can use Array and objects to represent and carry data. XML uses markup structure to carry data

JSON uses key value pair and array object that allows direct mapping of data structure of appropriate language.

XML allows namespace to avoid name conflicts this is not available in JSON.

JSON Formatter and Validator

JSON Formatter are used to provide structure way to JSON data.

JSON validators are tool that are used to validate JSON data.

Why JSON formatter and validator required.

If you get data from server it is in unformatted way

Like I get JSON data from url

api.openweathermap.org/data/2.5/weather?q=London

This will provide me weather information of London

JSON response from api.openweathermap.org
FIg: JSON response from api.openweathermap.org

Above JSON data is difficult to read we have to format above data to make it readable.

Few online tools that can be used are

JSONLint – The JSON Validator

JSON Formatter & Validator

and many more

put code received from URL to any one validator that validate and structure the data so that it can be readable

Formatted JSON from api.openweathermap.org
Fig: Formatted JSON from api.openweathermap.org
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select angularjs

Angularjs provides way to bind HTML select element with angularjs model

select directive also provide dynamic option value using ng-repeat and ng-options

When the item from select element is get selected from option then it is bind with the value of ng-model associated with select element using angularjs two way binding.

Setting option value using value attribute of option element will set this value as string.

On selection this value in ng-model the model variable must be string type.

https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.8/angular.min.js

select is

description of parameters fields are self explanatory.

To access value in model you have to provide modal name rest attributes are optional as per requirement any one can use.

let us see one basic example for selecting a value in model

Example

populating select with dynamic values

selecting a id based on value from json array as below

To select multiple in above program use multiple with select element as below

by holding control key with click can select multiple values

Using ng-option with select to generate dynamic option value

pre populating any specific value in ng-options is easy in following example you can see this.

Consider we have to populate Blue as default value then set $scope.favouriteColor=3 in controller

see below

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JavaScript Overlays

There are different kinds of overlays for modal dialogs for prompting,

overlays for info or warning boxes, tabbed overlays, alerting usersoverlays for displaying complex data.

The overlay can implement on HTML like images, links, forms, tables, any type of div and any can be styled with CSS, like rounded borders, shadows or gradients etc.

Core behaviors are configurable such as positioning, animation durations and closing the overlay.

Overlay offers a good container for other tools. Think of scrollables, tabs or accordions inside the Overlay.

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Array of pointers in C Programming

Example: Write a program to assign the address of array elements to pointer variable and print the array element with address.

OUTPUT

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While Statement in C Programming

“while loop” repeats a set of statements if condition is true. If condition is false the flow of control do not enter inside of while loop.

It first tests the condition then execute the body of loop.

Syntax of a while statement−

Example: Write a program to print 1 to 10 using while loop.

OUTPUT

Description: In the above program, line “while( a <= 10 )” will check if condition is true or false.

In the above case when a=1, condition is true and flow of control move inside of while and print 1 after that increment occurs.

Now a=2, again condition is true and flow of control move inside of while and print 2 after that increment occurs.

Now a=3, again condition is true and flow of control move inside of while and print 3 after that increment occurs.

This process is continue until condition is false(in this case condition false occur when a=11).

Example: Write a program to print 10 to 1 using while loop.

OUTPUT

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Switch Statement in C Programming

“switch” is a case control structure.

 It contains case and default values.

“switch” statement takes a value as a expression for equality testing against a list of values/case.

syntax for a switch statement:-

Rules of switch statement −

In a “switch” statement we can have any number of case.

for equality testing against a list of values/case, constant-expression for a case must be the same data type as the variable in the switch expression.

When “switch” expression value is equal to a case, the statements following that case will execute until a break statement is reached/executes.

When a break statement is reached/executes, the switch statement terminates, and the control jumps to the outside of switch.

break is a optional. If there is no break in the switch case, the flow of control will jump to the next case of switch until a break is reached.

switch statement also have a default case, which appear at the end of the switch. when none of the cases is true  then default case will execute.

No break is needed in the default case. “default” case is also an optional.

Example: Write a program to take one numbers from user between 1 to 3. Write entered number in words if number between 1 to 3 otherwise print wrong number using switch.

OUTPUT

Note: In the above program, for example user enters a number 6 then output will be as follows:

Example: Write a program using switch statement but without break.  

OUTPUT

Description: Because if there is no break in the switch case, the flow of control will jump to the next case of switch until a break is reached.

Note: In the above program, for example value of char variable c = ‘ A’ then the output will be as follows:

Nested switch statements

In C programming language we can define switch statement within another switch.

Syntax for a nested switch statement: −

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if else statement in C programming

In the C language decision making statement is executes if the given condition is true otherwise conditional block will never execute.

In C language non-zero and non-null values are consider as true, and zero or null values are consider  false.

if statement

Syntax of an if statement −

In a if statement if the expression result is non zero true, then the block of statement of the ‘if’ statement will be executed. If the expression result is zero, then the block of statement of the ‘if’ statement will not executed and control sent to the next line of if block.

Example: Write a program to demonstrate the ‘if’ statement.

OUTPUT

In the above program if(x>y) then the condition will be false and ‘if’ block will never execute.

OUTPUT

if-else  statement

Syntax of an ‘if-else’ statement −

Example: Write a program to take two numbers from user and find the grater between them using ‘if-else’ statement.

OUTPUT

Nested If else

In a C language we can use if statement inside another if statement(s).

Syntax of an ‘nested -if’ statement −

Example: Write a program to take two numbers from user if both number are between 1 to 9 then print “Good” using nested-if statement.

OUTPUT

Nested if else statement

In a C language we can use if or if-else statement inside another if or  if-else statement(s).

Syntax of an ‘if-else’ statement −

Example: Write a program to take three numbers from user and find the grater among them using ‘nested if-else’ statement.

OUTPUT

If else ladder

some times if can be nested inside else as below

above statements can be written as

OUTPUT

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Assignment Operators in C Programming

In a C language there are following assignment operators  −

Operator Description Example
= assignment operator (it assigns values of right side operands to left side operand ) a=5
+= Add assignment operator a+=5
-= Subtract assignment operator a-=5
*= Multiply  assignment operator a*=5
/= Divide assignment operator a/=5
%= Modulus assignment operator a%=5
<<= Left shift assignment operator a<<=5
>>= Right shift assignment operator a>>=5
&= Bitwise AND assignment operator a&=5
^= Bitwise exclusive OR assignment operator a^=5
|= Bitwise inclusive OR assignment operator a|=5

EXAMPLE: Use of assignment operators with arithmetic operators

Output

EXAMPLE: Use of assignment operators with bitwise operators

Output

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Bitwise Operators in C Programming

In a C programming language Bitwise operator works on bits and perform bit-by-bit operation. There are following bitwise operators in C:-

Operator Description Example
& Binary AND Operator   a & b
| Binary OR Operator a| b
^ Binary XOR Operator  a^b
~ Binary One’s Complement Operator is unary ~a
<<  Binary Left Shift Operator a<<b
>>  Binary Right Shift Operator a>>b

The truth tables for &, |, and ^ is as follows –

a b a & b a | b a ^ b
0 0 0 0 0
0 1 0 1 1
1 1 1 1 0
1 0 0 1 1

Assume A = 60 and B = 13 in binary format, they will be as follows −

               A in binary     = 0011 1100         (60)                     

              B in binary     = 0000 1101          (13)

Bitwise AND (&)

                      A      = 0011 1100         (60)                

          &         B      = 0000 1101          (13)

———————————————————

                                0000 1100           (12)

Bitwise OR (|)

                      A      = 0011 1100         (60)                

          |          B      = 0000 1101          (13)

———————————————————

                                0011 1101           (61)

Bitwise XOR (|)

                      A      = 0011 1100         (60)                

          ^         B      = 0000 1101          (13)

———————————————————

                                0011 0001           (49)

Binary Left Shift Operator

Left shift operator shift all the bits in a left direction to specified number of times.

i=16 //0001 0000

Example:

Binary Right Shift Operator

Left shift operator shift all the bits in a left direction to specified number of times.

int i = 16;                    // 0001 0000

i = i>>2;                      // 0000 0100  (shift right 2 bits, last 2 bits will be lost, and 2 zero add in front)

Example

Output

Exapmle:  Write a program to demonstrate Bitwise operator.

OUTPUT

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Relational Operators in C Programming

C Language has a following relational operators. For example: Assume variable A holds 100 and variable B holds 200 then −

Operator Description Example
== Equals to (A == B) is not true.
!= Not equal (A != B) is true.
Greater than (A > B) is not true.
Less than (A < B) is true.
>= Greater than or equals to (A >= B) is not true.
<= Less than or equals to (A <= B) is true.
Example: Write a C Program to find the largest of two numbers.

Output

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