What is flow control in Julia?

Flow control in Julia is the different constructs offered by the language to control the flow of execution/control in the program.

Julia provides the following flow control constructs:

  1. Conditional if-elseif-else construct
  2. Short-circuit evaluation
  3. Repeated evaluation via loops.

Conditional construct

The if-elseif-else is a conditional construct used to execute a block of code based on a boolean expression’s value.

The basic syntax of if-elseif-else is as follows:

if boolean-expression
   block-of-code
elseif boolean-expression
   block-of-code
else
   block-of-code
end

Code example

Let’s look at the code below:

a = 5
b = 10
if a > b
   println("a > b")
elseif b > a
   println("b > a")
else
   println("a = b")
end

Short-circuit evaluation

Short-circuiting is a programming concept where the compiler bypasses some logical expressions, sub-expressions, execution, or evaluation. Once the expression’s value has been established, the compiler stops analyzing the subsequent subexpressions. For this purpose, Julia’s && and || operators are used, which stand for logical “and” and “or”, respectively.

  • x && y: The subexpression y is only evaluated if x evaluates to true.
  • x || y: The subexpression y is only evaluated if x evaluates to false.

Code example

Let’s look at the code below:

#include <iostream>
using namespace std;
int main() {
  // your code goes here
  cout << "Hello World";
  return 0;
}

Repeated evaluation via loops.

There are two constructs for repeated evaluation via loops.

  1. for loop
  2. while loop

Note: To understand more about the loops, refer to For vs. While loop in Julia .

Code example

Let’s look at the code below:

print("Using for loop:\n")
arr = [1,2,3,4,5]
for i in arr
    print(i, " ")
end
print("\nUsing while loop:\n")
num = 1
while num <= 5
  print(num, " ")
  num+=1
end

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