difference between like '%%%var%%' and '%var%'

1. What is difference between $VAR and $ var?
2. What is the difference between undefined value and null value in term of object's value?
3. What is difference between VAR and string?
4. What is difference between let Var and Const?
5. What is difference between and $$ in PHP?
6. What is the difference between dollar message and Dollar Dollar message?
7. What is == and === in JavaScript?
8. Should I use null or undefined?
9. Is null == undefined?
10. What string means?
11. Why VAR is used in C#?
12. What is DART VAR?

What is difference between $VAR and $ var?

In an array, "[i]f the word is double-quoted, $name[*] expands to a single word with the value of each array member separated by the first character of the IFS variable, and $name[@] expands each element of name to a separate word."

What is the difference between undefined value and null value in term of object's value?

The null value is a primitive value which represents the null, empty, or non-existent reference. The undefined value is a primitive value, which is used when a variable has not been assigned a value.

What is difference between VAR and string?

Var is used to declare Implicitly typed variable where the compiler identifies the type automatically. var can hold any type of data. String is an explicit declaration for holding string data only. ... 'string' is a particular data type which can hold only string data and not of any type.

What is difference between let Var and Const?

var declarations are globally scoped or function scoped while let and const are block scoped. var variables can be updated and re-declared within its scope; let variables can be updated but not re-declared; const variables can neither be updated nor re-declared. They are all hoisted to the top of their scope.

What is difference between and $$ in PHP?

The $ operator in PHP is used to declare a variable. ... The $var_name is a normal variable used to store a value. It can store any value like integer, float, char, string etc. On the other hand, the $$var_name is known as reference variable where $var_name is a normal variable.

What is the difference between dollar message and Dollar Dollar message?

$message is used to store variable data. $$message can be used to store variable of a variable. Data stored in $message is fixed while data stored in $$message can be changed dynamically.

What is == and === in JavaScript?

== in JavaScript is used for comparing two variables, but it ignores the datatype of variable. === is used for comparing two variables, but this operator also checks datatype and compares two values. Checks the equality of two operands without considering their type. Compares equality of two operands with their types.

Should I use null or undefined?

When a variable or a property on an object does not have a value it is undefined , and for a value to be null you need to assign it a null value. As the variable already has no value there is absolutely no point in declaring that again with another type that in the end has the same meaning.

Is null == undefined?

Introduction. Null and Undefined are both data types in JavaScript. Undefined is a variable that has been declared but not assigned a value. ... So you can assign the value null to any variable which basically means it's blank.

What string means?

noun. a slender cord or thick thread used for binding or tying; line. something resembling a cord or thread. Also called cosmic string . Physics.

Why VAR is used in C#?

By using “var”, you are giving full control of how a variable will be defined to someone else. You are depending on the C# compiler to determine the datatype of your local variable – not you. You are depending on the code inside the compiler – someone else's code outside of your code to determine your data type.

What is DART VAR?

In Dart, The var keyword is used to declare a variable. The Dart compiler automatically knows the type of data based on the assigned to the variable because Dart is an infer type language.