Functions in Carbon Language

Types of Calling Methods 

There are two different types of calling methods in Carbon, like C++: 
 

1. Call By Value
2. Call By Reference 

Call By Value

This method copies the values of the actual parameters into the formal parameters,i.e., the function creates its copy of the argument value and then passes it.

To understand, let us take an example.

Suppose you have been given a juice bottle ( formal parameters ) for testing. You tried, and you liked it. The original bottle ( actual parameters ) is still full, so the juice you drank didn't reflect the original one. 

This is precisely the meaning of Call By Value. Henceforth, any modification in the formal parameter doesn't reflect back to the actual parameters during call-by-value.

Let us see an example to understand the Call by Value better: 

package test api;
fn Sum(var x: i32, var y: i32) -> i32{
   return x + y;
}
fn PrintSum(var x: i32, var y: i32){
   x = 0;
   Print(Sum(x,y));
}
fn Main() -> i32{
   var a: auto = 1;
   PrintSum(a,2);
   Print(a);
   return 0;
}

Output

Explanation: In the above example, we are finding the sum of two variables which are x and y. 

• The value of a set to 1 in the main function.
   
• We have another function, named Sum , that is finding the sum of two variables.
   
• Last, we have the PrintSum function which is printing the values. 
   
• Since the call by value is employed, the changed value inside the function must not reflect the original value. 

Let us now have a look at Call By Reference method:
 

Call By Reference

As the name indicates, a reference to the original variable is passed rather than passing a value to the function being invoked. 

• When a function is invoked by reference, the formal parameters become references to the actual parameters. 
   
• This means that the invoked function does not create its copy of original values; rather, it refers to the original values only by different names, i.e., the references. 
   
• Henceforth, the invoked function works with the original values, and any alteration in the values gets reflected back to the original one.

To understand the call by Reference concept, you must be familiar with Pointers in Carbon. 

What are Pointers?

A pointer is a type of variable that holds the memory address of another type of variable as its value. 

• To declare a pointer put * after the type.
• To dereference put * before the variable name.
• To get the address of a variable, put & before the variable name.

Now, let us see an example of Call By Reference:

In the example below, there is a function named Increment which is incrementing the value of x by 1. Since we are applying a call by reference technique, the output must return the updated or reflected result performed by the function. 

package test api;
fn Increment(var x: i32*){
   // incrementing the x by 1
   *x = *x + 1;
}
fn Main() -> i32{
  var a: auto = 1;
  // call by reference
  Increment(&a);
  Print("{0}", a);
  return 0;
}

Output

So far we have discussed Functions in Carbon, let us now have a look at some faqs based on the above discussion. 

Frequently Asked Questions

When was the Carbon language introduced?

Carbon language was introduced in July 2022 by a Google engineer.

Is Carbon language Bi-directional?

Carbon language is Bi-directional as it allows us to call C++ language code from Carbon and also Carbon language code to C++.

Why is Carbon an open-source language?

The open-source approach is very effective and successful for languages like Carbon. It is important to have a broad community working on improving it. The project is developed in such a way to be contributed by both small and large players.

How are variables declared in Carbon?

Variables are declared with the var keyword. The : is used after the variable names. Example: var x: i32 = 7. The integer type is specified by i32 in this example.

Conclusion 

To conclude the discussion, we explored Functions in Carbon Language. We have also looked at types of functions in Carbon Language. At last, we have looked at types of function invocation techniques with examples. 

If you want to enhance your knowledge on Carbon language, you can check out our other articles-

👉 Data types in Carbon

👉 Variables in Carbon

👉 Strings in Carbon

👉 Data Types in C++

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