Add support for my favourite number 2,452,739. Would greatly appreciate it. Compliments to the code, it is very simple, easy to understand and flawless.
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This is a very interesting problem, I’ve proposed a solution to the exact same issue a while back, it may be useful; How to check number is even or odd - #5 by Hexadecagons
checking each individual number instead is far more complicated than just checking the last digit
Its not complicated you just add every number to the list
I hope these people know they aren’t funny 
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i am lost at what’s happening in this thread 
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Summary
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Yk, it’s basic lua xd, soo it is not complicated, it’s normal way, a lot of elseifs are not practical way, for loop is best option to do that
Why One Million elseif Statements Are More Optimized Than a for Loop: A Technical Exploration
Introduction:
At first glance, one might assume that using a loop structure, such as a for loop, would be the most efficient way to handle large amounts of repetitive conditional logic in Lua. However, under certain circumstances, utilizing a vast number of elseif statements—up to one million—can provide superior optimization in terms of both execution speed and memory usage. This conclusion stems from the way Lua handles conditional branching, bytecode generation, and machine-level instructions.
In this detailed exploration, we will demonstrate how one million elseif statements, despite appearing excessive, could be more efficient than a for loop for certain scenarios. We’ll delve into the Lua interpreter, bytecode, and the underlying hardware interactions that make this possible.
1. Understanding the elseif Versus for Loop Dichotomy
At a high level, the for loop is designed for iterating over sequences and executing the same block of code repeatedly, whereas elseif statements provide conditional branching. In most programming languages, loops are considered optimal for repetitive tasks. However, the Lua interpreter has unique characteristics that allow elseif statements to outperform loops in specific situations—particularly when evaluating distinct conditions.
Consider the following scenario where one million conditions must be checked:
Using One Million elseif Statements:
if condition1 then
-- action1
elseif condition2 then
-- action2
-- ...
elseif condition1000000 then
-- action1000000
else
-- default action
end
Using a for Loop for the Same Task:
for i = 1, 1000000 do
if conditions[i] then
-- perform action for condition i
end
end
At first glance, the for loop might seem more concise and manageable. However, we need to consider the underlying optimizations performed by Lua when executing such large-scale conditional logic.
2. Lua Bytecode and Conditional Branching
When Lua compiles a sequence of elseif statements, it generates a highly optimized bytecode structure that minimizes the number of operations required to evaluate each condition. The key to this efficiency lies in Lua’s handling of conditional jumps.
For each elseif, Lua generates a conditional branch that either executes the relevant action or skips to the next branch based on the evaluation of the condition. Importantly, Lua’s bytecode compiler is designed to optimize jump tables for such conditions, allowing the VM to rapidly navigate through the million elseif conditions without redundant evaluations.
For example, the Lua bytecode for a large elseif chain might look something like this:
GETUPVAL 0 0 ; load condition1
TEST 0 0 ; if false, jump
JMP 4 ; jump to action1
GETUPVAL 0 1 ; load condition2
TEST 0 0 ; if false, jump
JMP 7 ; jump to action2
-- Repeated for each elseif condition
With this bytecode structure, the Lua interpreter can leverage jump optimization techniques to quickly bypass large sections of the elseif chain if necessary, without needing to evaluate each condition sequentially. This is in contrast to a for loop, which requires a more complex evaluation of the loop control variable and condition array for each iteration.
3. Machine Code Generation and Jump Optimization
Once the Lua bytecode is generated, it is translated into machine code, where the efficiency of the elseif chain truly becomes apparent. Each elseif corresponds to a conditional jump at the machine code level, which is one of the most optimized instructions on modern CPUs. These jumps can be executed in just a few CPU cycles, with very little overhead.
A for loop, on the other hand, introduces additional complexity at the machine level. The loop requires the maintenance of a loop control variable (i in this case), comparison of the variable against a termination condition, and the overhead of incrementing the variable with each iteration. These operations introduce additional instructions, such as CMP (compare), INC (increment), and JMP (jump), that must be executed on each iteration of the loop.
The elseif structure, by contrast, avoids the need for loop control and focuses purely on conditional branching. In the case of one million elseif statements, this can lead to a reduction in the total number of instructions executed by the CPU.
4. CPU-Level Considerations: Pipeline Efficiency and Cache Hits
Modern CPUs rely on instruction pipelines to execute multiple operations concurrently, maximizing performance by overlapping instruction execution. The fewer instructions that are required, the more efficient the pipeline becomes. Since elseif chains minimize loop-related instructions, they allow the CPU’s pipeline to operate more smoothly.
Moreover, CPUs have limited instruction cache capacity, which stores recently executed instructions for quick retrieval. A for loop, with its repetitive instructions (such as incrementing and comparison), can lead to cache misses, where the CPU must reload instructions from memory. By using a long elseif chain, Lua’s bytecode avoids this issue by keeping the control flow streamlined with minimal branching overhead, leading to fewer cache evictions and faster execution.
5. Memory Overhead: Reduced Stack Operations
In a for loop, each iteration requires the Lua interpreter to push and pop values to and from the stack, particularly the loop control variable and the array of conditions. This incurs a memory overhead that grows with the number of iterations. Additionally, the array of conditions must be stored and accessed in memory, which can increase memory usage, especially when dealing with one million conditions.
By contrast, an elseif chain has a more static memory footprint. Each condition is handled independently, and there is no need for an array to store conditions. The interpreter directly evaluates each condition without the additional memory operations required by a for loop.
6. Predictive Branching and CPU Optimization
Modern CPUs use branch prediction to guess the outcome of conditional jumps, allowing them to speculatively execute instructions. In a well-optimized elseif chain, the CPU can often predict the outcome of conditional jumps with high accuracy, reducing the impact of mispredictions. The more straightforward and predictable the control flow, the better the branch predictor performs.
A for loop, however, introduces a level of unpredictability due to the loop control variable. Each iteration requires a comparison, and the branch predictor must handle the possibility that the loop will terminate on any given iteration. This increases the likelihood of mispredictions, leading to potential pipeline stalls and decreased performance.
Conclusion:
In certain contexts, utilizing one million elseif statements can be more optimized than using a for loop. The efficiency stems from Lua’s ability to generate streamlined bytecode for conditional branching, reduced complexity at the machine code level, and more efficient CPU pipeline execution. While a for loop may seem like the intuitive choice for repetitive tasks, the control flow and memory overhead associated with loop operations can introduce performance bottlenecks, particularly when scaling to large numbers of conditions.
By leveraging the optimization potential of elseif statements, you can achieve faster execution and lower memory usage in situations where each condition is evaluated independently.
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came here expecting a “yanderedev code” comment, found an essay on why elseif > loops
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I am a proffesional coder. This is for the character limit.
damn i really cant look up stuff huh
anyways, when is this thread dying? please use modulo
moadudailes or howberey u say it is very inefficient look at the replies abovce
Each conditional branch consumes memory. Each elseif condition is checked sequentially, so with a large number of conditions, the time taken to evaluate them increases linearly.
At this rate you guys will be actual programmers in about 1300 years.
function isEven(number)
return number % 2 == 0
end
function isOdd(number)
return number % 2 ~= 0
end
Pick one.
No programmer would even think of using that many ifs or elseifs line up that long.
Is the help section a joke to you? How is this even here?
i cant find said reply (apart from one comment by you with no source or continuation)
i would like to have more information on this if possible
They have like 500 million elseif statements not one million
Is this a troll? What exactly do you need help with? Most people don’t know numbers above one million exist so you should be good
This is 9 year old humor. Insulting to the help section, making a mockey of it.
Not every thread has to be serious, it’s not like there’s dozens like this on the front page; it’s a single one. Why so serious? grow up
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You asked if this thread was trolling. Just answering your question accurately. I am being serious because this is seriously the help section.