The IF conditional

The IF conditional is the simplest of conditionals. It is a control structure that evaluates a condition and executes a block of code if that condition is true.

In natural language, the IF conditional means,

If this happens 🡆 do this

Represented as a diagram, it would look something like this:

Translated into code, it would look like this:

if(condition)
{
    // Code to execute if the condition is true
}

The condition is an expression that must be evaluable as true or false. If the condition is true, the block of code inside the IF conditional is executed. Otherwise, the block is skipped and the program continues with the next instruction.

Here are some examples of valid conditions to use in IF conditionals,

if(true) // with a literal. It doesn't make much sense, but it works

if(a < 3)  // examples like comparison
if(a == 3)
if(a != 3)

var isValid = true
if(isValid) // boolean variable

if(1)  // in some languages, certain literals are automatically evaluated to true or false

if(calcularIsValid())   // call to a function that returns a boolean

On the other hand, the code to execute if the condition is true can generally be,

• A single instruction
• A block

if(condition)
    // a single statement to execute

if(condition) 
{
    // a block with actions to execute
}

Examples of IF conditionals in different languages

Virtually all programming languages have an IF conditional. Let’s see it with an example.

• We will evaluate a variable containing a person’s height
• If it is greater than 1.90, the person is very tall

if (height > 1.90)
{
    // show message 'Wow! You are very tall!' 😮
}

if ($height > 1.90)
{
    // show message 'Wow! You are very tall!' 😮
}

if height > 1.90:
    # show message 'Congratulations! You have passed' 😮

If height > 1.90 Then
    ' show message 'Congratulations! You have passed' 😮
End If

As we can see, in general, all IF conditionals have the same structure and functionality, with small syntax differences between languages.

Internal Functioning Advanced

Under the hood, an IF conditional is a bifurcation of the normal program flow. For this, a conditional jump instruction is used. This is similar to a GO-TO jump instruction but is only executed if a condition is met.

Depending on the architecture, different conditional jumps are available. For example, if two values in memory are equal, or different, etc.

Therefore, there are several ways to execute the conditional jump. For example, the one I put in the diagram is the simplest.

• If the condition is true, the program continues, executing the code
• If the condition is false, the program jumps, and does not execute the body of the code

Which, as we see, is exactly the behavior we said an IF conditional has.