C#•7d ago

scope of a for loop

what is the scope of i in for (int i = 0; i < Length; i++) { }? does it only exist within the for loop? if i want i to be used outside, i need this right?

i = x
for (int i = 0; i < Length; i++) { }

i = x
for (int i = 0; i < Length; i++) { }

this would break?

for (int i = 0; i < Length; i++) { }
x = i

for (int i = 0; i < Length; i++) { }
x = i

88 Replies

سَلْمَانْ حَيدَرْ•7d ago

$tias

MODiX•7d ago

https://images-ext-1.discordapp.net/external/CO2vsU2aXbRqYy1RdewOYnkBq1nGFBjdbjlNgjvG67A/https/media.discordapp.net/attachments/364492811489509376/964064233035816990/unknown.png?width=543&height=257

ElectricTortoiseOP•7d ago

ok fair enough i want my code to look neat tho and ChatGPT did this

int i = 0;
for (; i < Length; i++)
{
  //Do stuff
}

int i = 0;
for (; i < Length; i++)
{
  //Do stuff
}

It can do that??? How does the for loop know what to use in front of the ;

سَلْمَانْ حَيدَرْ•7d ago

lmao why are you doing that

ElectricTortoiseOP•7d ago

i should show the full code hang on

int numberOfCaptures = 0;
for (; numberOfCaptures < moveList.Length; numberOfCaptures++)
{
    if ((moveList.Moves[numberOfCaptures] >> 12) != (int)MoveFlag.Capture)
        break;
}

int numberOfCaptures = 0;
for (; numberOfCaptures < moveList.Length; numberOfCaptures++)
{
    if ((moveList.Moves[numberOfCaptures] >> 12) != (int)MoveFlag.Capture)
        break;
}

سَلْمَانْ حَيدَرْ•7d ago

dont do that just use the normal for loop syntax

ElectricTortoiseOP•7d ago

right now, moveList is a bit longer than numberOfCaptures so i wanna count numberOfCaptures

int numberOfCaptures;
for (numberOfCaptures = 0; numberOfCaptures < moveList.Length; numberOfCaptures++)
{
  if ((moveList.Moves[numberOfCaptures] >> 12) != (int)MoveFlag.Capture) { break; }
}

int numberOfCaptures;
for (numberOfCaptures = 0; numberOfCaptures < moveList.Length; numberOfCaptures++)
{
  if ((moveList.Moves[numberOfCaptures] >> 12) != (int)MoveFlag.Capture) { break; }
}

so like that?

سَلْمَانْ حَيدَرْ•7d ago

i dont get it why do you need to do this , you should use normal for loop syntax, if you need to keep track of a value e.g count then use an extra variable

ElectricTortoiseOP•7d ago

i need numberOfCaptures to splice the array im working with so my plan is to count it first, then make another loop going up to numberOfCaptures only

Jimmacle•7d ago

it doesn't "know" anything, all 3 expressions inside a for loop's parentheses are optional for (;;) is valid code

ElectricTortoiseOP•7d ago

ooo

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ElectricTortoiseOP•7d ago

lmfaoooo true true the LLM sucks

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ElectricTortoiseOP•7d ago

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ElectricTortoiseOP•7d ago

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ElectricTortoiseOP•7d ago

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ElectricTortoiseOP•7d ago

not really

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ElectricTortoiseOP•7d ago

lmfao

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ElectricTortoiseOP•7d ago

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ElectricTortoiseOP•7d ago

i try my best to understand the code im doing

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ElectricTortoiseOP•7d ago

but sometimes it's hard to find good sources

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ElectricTortoiseOP•7d ago

ChatGPT is surprisingly organised even though the code it spits out is broken half the time

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ElectricTortoiseOP•7d ago

yea that's what i use it for mostly

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ElectricTortoiseOP•7d ago

yea so i didnt copy paste the result i came here to ask what the result is doing

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ElectricTortoiseOP•7d ago

ummmm ok so... what's the scope of a for loop that was the question i came here with

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ElectricTortoiseOP•7d ago

for (int i = 0; i < Length; i++) { }
x = i

for (int i = 0; i < Length; i++) { }
x = i

but i is declared within for()

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ElectricTortoiseOP•7d ago

so this wont work but then where is the i defined jimm said for(;;) is legal

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ElectricTortoiseOP•7d ago

int i = 0;
for (; i < Length; i++)
{
  //Do stuff
}

int i = 0;
for (; i < Length; i++)
{
  //Do stuff
}

and this was GPT's code

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ElectricTortoiseOP•7d ago

ooo i havent

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ElectricTortoiseOP•7d ago

mmmm ok

SG97•7d ago

and stop using gipity

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ElectricTortoiseOP•7d ago

ngl i kinda overlooked the for loop's docs bcs i use it so often in the for (int i = 0; i < Length; i++) so like i kinda assumed that was it never really thought about what goes on behind the scenes tho

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ElectricTortoiseOP•7d ago

i only use it as a glorified search engine when google wont tell me what i want

SG97•7d ago

aight

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ElectricTortoiseOP•7d ago

aha so it's a glorified while loop

ElectricTortoiseOP•7d ago

ooooooooo ok

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ElectricTortoiseOP•7d ago

wowzers ok

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ElectricTortoiseOP•7d ago

ooo ok also after reading just a small part of the docs i think i understand what ChatGPT did

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ElectricTortoiseOP•7d ago

It did not include the initializer, so C# defaulted to using whatever value the variable had beforehand

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ElectricTortoiseOP•7d ago

is that correct

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ElectricTortoiseOP•7d ago

makes sense makes sense just had a stupid idea: can you use a for loop as a while loop

FusedQyou•7d ago

tl;dr This is fine, a for loop is not required to define a variable to loop, but it does require the semicolons to be defined. As jimmacle mentioned this makes for(;;) valid but it would be the same as an infinite while loop. Depends on use case This is wrong, no such thing as a "normal" loop and what they wrote is very valid Finally, scope is anything in {} brackets. You should understand that scope is not a strict thing and {} is valid anywhere in the code, not just if-statements or things like that. You can nest {} infinitely and it would technically make a new scope each time. It's just most commonly used in for-loops/if-statements/while-statements because they are tied to execute a single line otherwise and this way you execute a whole scope. I personally use scopes if I have common names for variables and I define them multiple times, but they vary per context. It's nice being able to wrap them in {} so the scope gets rid of the name so I can just redefine them later.

ElectricTortoiseOP•7d ago

oh so i can literally just place {} anywhere and it would define a scope?

FusedQyou•7d ago

Yes

void Main()
{
  int foo = 0;

  {
    int bar = 0;

    // Legal, defined in parent scope
    foo = 5;
  }

  // Not legal, defined in disposed scope
  bar = 5;
}

void Main()
{
  int foo = 0;

  {
    int bar = 0;

    // Legal, defined in parent scope
    foo = 5;
  }

  // Not legal, defined in disposed scope
  bar = 5;
}