Var And Var! In Microsoft Bosque Programming Language

All programming languages have one central area that is used to declare the variables. In this article, we are going to learn how to declare a variable in Bosque programming.

var is used to declare the variable and the var keyword can be divided into two different types:

var
var!

var statement is used to declare a const variable
var! is used to declare a non-const variable.

var variable

We can declare the variable in two different ways.

var Identifier = exp;
var identifier : Datatype = exp;

The example declaration code is given below.

var x:Int = 3; // variable declare as int and initialized.
var x =” Hello World”; // variable introduced and inferred to be of type string

Once a variable has initialized, it can't be changed at a later point. In the below sample code, a variable is initialized as “Hello World” and is later changed to “Welcome Bosque.”

namespace NSMain;
entrypoint
function main(): String {
var x2 = "Hello World";
x2 = "Welcome bosque";
return x2;
}

Compile the program. The Bosque compiler throws a parse error “variable defined as const.”

var! variable

In the case of var! the syntax can be modified by assignment statements. We can declare the var! variable in three different types. Two types are the same as var declaration while the third one is only a datatype declaration without initialization.

var !identifier: Type;
var !Identifier = exp;
var !identifier: Datatype = exp;

Below is the sample code using var!

namespace NSMain;
entrypoint
function main(): String {
var !x2 = "Hello World";
x2 = "Welcome bosque";
return x2;
}

var! must define the datatype or should be initialized otherwise compiler throws an error. In the below code, we have declared only a variable without defining the datatype or without initialization.

namespace NSMain;
entrypoint
function main(): String {
var !x;
return x;
}

Compile the program. The Bosque compiler throws an error.

var and var! assignment

var! is a variable that can be assigned to the var variable. The only rule is that var! must be initialized before assigning to var otherwise compiler throws an exception.

The below code shows that var! only is declared not assigned any value and it is assigned to var variable “x”.

namespace NSMain;
entrypoint
function main(): String {
var !x: String;
var x1 = x;
return x;
}

Compile the program. It throws an error.

Before assigning to var x1 = x, initialize the x variable, then it will work out.

namespace NSMain;
entrypoint
function main(): String {
var !x: String;
x = "Difference between var and var!";
var x1 = x;
return x1;
}

Run the program.

Conclusion

I hope you can understand the use of var and var! and the differences between them.

Happy Coding!!!

3 Comments

Join the conversation! Your thoughts help the community grow.

Sarathlal Saseendran7y ago
Something different and interesting Vinoth. Thanks for sharing.
Mahesh Chand7y ago
Nice Vinod. You may want to put links to your previous article for someone who finds this article. Cheers!
- Vinoth Rajendran7y ago
  Thanks Mahesh, Sure