Chapter 7

Lets we repeat some name

How can i make "jane doe you are funtastic" with 50 times?, should i create 50 statement of prints ?. Absolutely no, we can use looping.

For Loop

The for loop repeats a block of code a specified number of times:

for (var increment: int = 0; increment < 50; increment++) {
    std::print("jane doe you are funtastic");
}

increment variable are incremental value that always change until statement < 50 become false, so, the value will start from 0 -> 1 and ends with 49 because 0 are including.

For Loop Syntax

for (init; condition; increment) {
    // body
}

Part	Description
`init`	Executed once before the loop starts (e.g., `var i = 0`)
`condition`	Evaluated before each iteration; loop continues if true
`increment`	Executed after each iteration (e.g., `i++`)

For Loop with std::print

include std;

for (var i = 0; i < 20; i++) {
    std::print("{}\n", i);
}

Output:

For Loop with Increment/Decrement

// Count up
for (var i: int32 = 0; i < 5; i++) {
    std::print("{}", i);  // 0, 1, 2, 3, 4
}

// Count down
for (var i: int32 = 5; i > 0; i--) {
    std::print("{}", i);  // 5, 4, 3, 2, 1
}

For Loop Example

for (var i: int32 = 0; i < 5; i++) {
    std::print("Iteration: {}", i);
}
// Output: 0, 1, 2, 3, 4

While Loop

The while loop repeats as long as a condition is true:

var increment: int = 0;

while (increment < 50) {
    std::print("jane doe you are funtastic");
    increment++;
}

When to Use While vs For

Loop Type	Use Case
`for`	When you know the number of iterations
`while`	When you don't know how many iterations needed

We can using while looping, its look more logically but its very different from for. while are used if we don't know how much will count it, for loop basically we know how much we need to repeat some statement.

While Loop Syntax

while (condition) {
    // body
}

Break Statement

The break statement exits the loop immediately:

var i: int32 = 0;
while (i < 100) {
    if (i == 10) {
        break;  // Exit the loop when i reaches 10
    }
    std::print("{}", i);
    i++;
}
// Output: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Break in For Loop

for (var i: int32 = 0; i < 100; i++) {
    if (i == 20) {
        break;  // Stop at 20
    }
    std::print("{}", i);
}
// Output: 0 through 19

Continue Statement

The continue statement skips the rest of the current iteration and moves to the next one:

for (var i: int32 = 0; i < 10; i++) {
    if (i % 2 == 0) {
        continue;  // Skip even numbers
    }
    std::print("{}", i);  // Only prints odd: 1, 3, 5, 7, 9
}

Continue in While Loop

var i: int32 = 0;
while (i < 10) {
    i++;
    if (i % 2 == 0) {
        continue;  // Skip even
    }
    std::print("{}", i);  // Only odd: 1, 3, 5, 7, 9
}

Practical Examples

Finding an Element

var arr = [1, 2, 3, 4, 5];
var target: int32 = 3;
var found: bool = false;

for (var i: int32 = 0; i < 5; i++) {
    if (arr[i] == target) {
        found = true;
        break;  // No need to continue searching
    }
}

if (found) {
    std::print("Found!");
} else {
    std::print("Not found");
}

Skip Invalid Values

var count: int32 = 0;
var i: int32 = 0;

while (count < 10) {
    i++;
    if (i < 0) {
        continue;  // Skip negative values
    }
    count++;
    std::print("Valid: {}", i);
}

Infinite Loop with Break

var input: int32 = 0;

while (true) {
    if (input == 42) {
        std::print("You found the magic number!");
        break;  // Exit infinite loop
    }
    input = input + 1;  // In real code, this would be user input
}

Nested Loops

for (var i: int32 = 0; i < 3; i++) {
    for (var j: int32 = 0; j < 3; j++) {
        std::print("({}, {})", i, j);
    }
}
// Output: (0,0) (0,1) (0,2) (1,0) (1,1) (1,2) (2,0) (2,1) (2,2)

Increment and Decrement Operators

XVR supports both prefix and postfix increment/decrement:

Operator	Description	Example	Result
`++`	Postfix increment	`i++`	Returns old value, then increments
`--`	Postfix decrement	`i--`	Returns old value, then decrements
`++`	Prefix increment	`++i`	Increments, then returns new value
`--`	Prefix decrement	`--i`	Decrements, then returns new value

Example

var a: int32 = 5;
var b: int32 = a++;  // b = 5, a = 6
var c: int32 = ++a;  // c = 7, a = 7

Error Handling

Break/Continue Outside Loop

if (true) {
    break;  // ERROR: break must be inside a loop
}

Compiler output:

error: break statement must be inside a loop
help: place the 'break' statement inside a 'while' or 'for' loop

Non-Boolean Condition

var x = 5;
while (x) { }  // ERROR: condition must be boolean

Compiler output:

error: condition of while statement must be boolean, got 'i32'
help: use a comparison operator (e.g., 'x > 0') or wrap the condition with 'bool()'

LLVM IR Generation

Loops generate proper LLVM basic blocks:

For Loop IR

; for (var i = 0; i < 5; i++) { std::print(i); }
entry:
  %i = alloca i32
  store i32 0, ptr %i
  br label %for_cond

for_cond:                                   ; preds = %entry, %for_inc
  %i1 = load i32, ptr %i
  %lt = icmp slt i32 %i1, 5
  br i1 %lt, label %for_body, label %for_end

for_body:                                   ; preds = %for_cond
  %i2 = load i32, ptr %i
  call @printf(ptr @fmt, i32 %i2)
  br label %for_inc

for_inc:                                    ; preds = %for_body
  %i3 = load i32, ptr %i
  %inc = add i32 %i3, 1
  store i32 %inc, ptr %i
  br label %for_cond

for_end:                                    ; preds = %for_cond
  ret i32 0

While Loop IR

; while (i < 10) { i = i + 1; }
entry:
  br label %while_cond

while_cond:                                   ; preds = %entry, %while_body
  %cond = icmp slt i32 %i, 10
  br i1 %cond, label %while_body, label %while_end

while_body:                                   ; preds = %while_cond
  ; loop body code
  br label %while_cond

while_end:                                    ; preds = %while_cond
  ; code after loop

Best Practices

Avoid infinite loops unless intentional
Use break for early exit - clearer than complex conditions
Use continue for skipping - cleaner than nested if statements
Keep loops simple - extract complex logic to functions
Watch for off-by-one errors - test boundary conditions
Use for loops for counted iterations - more readable

// Good - clear loop condition
for (var i: int32 = 0; i < length; i++) {
    process(arr[i]);
}

// Avoid - confusing condition
for (var i: int32 = 1; i <= length - 1; i++) {
    process(arr[i]);
}

Summary

Statement	Description
`for`	Loop with known iteration count
`while`	Loop with condition
`break`	Exit loop immediately
`continue`	Skip to next iteration
`++` / `--`	Increment/decrement operators
Conditions	Must be boolean

for loops are best when you know the number of iterations
while loops are best when the number of iterations is unknown
break and continue provide fine-grained control over loop execution
Always ensure loops have a way to terminate
Use std::print() for formatted output with \n for newlines

Lets we repeat some name​

For Loop​

For Loop Syntax​

For Loop with std::print​

For Loop with Increment/Decrement​

For Loop Example​

While Loop​

When to Use While vs For​

While Loop Syntax​

Break Statement​

Break in For Loop​

Continue Statement​

Continue in While Loop​

Practical Examples​

Finding an Element​

Skip Invalid Values​

Infinite Loop with Break​

Nested Loops​

Increment and Decrement Operators​

Example​

Error Handling​

Break/Continue Outside Loop​

Non-Boolean Condition​

LLVM IR Generation​

For Loop IR​

While Loop IR​

Best Practices​

Summary​