Objective-C programming [closed] - objective-c

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*warning: iteration 5u invokes undefined behavior [-Waggressive-loop-optimizations]
if([user1 isEqualToString:account1[i].name])
^
main.m:33:2: note: containing loop
for(i=0;i<=6;i++)
^
please somebody correct this code

Almost certainly you have:
Thing account1[6] = { ... };
for (i = 0; i <= 6; i++)
{
if ([user1 isEqualToString:account1[i].name])
and the compiler knows that <= 6 will go beyond the bounds of the array (last index is 5 not 6).
To correct:
for (i = 0; i < 6; i++)
^

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Why can you not specify var/val loops in Kotlin? [closed]

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Why can't you specify a val or var type in for loop's in Kotlin. For example, I would like to be able to do
for (var i in 0...data.size - 1) {
for (j in 0..bytes.size - 1) {
bytes[j] = data[i++]//cant do i++ in current kotlin because "i" is val
}
//do stuff
}
But instead I have to do this
var i = 0
while (i < data.size) {
for (j in 0..bytes.size - 1) {
bytes[j] = data[i++]
}
//do stuff
}
Your example is slightly different from Java's typical for(int i=0;i<data.size;i++) example.
In the Kotlin version 'i' is actually an element of the range in which case i++ doesn't make sense. It just so happens that the range you have is a list of indexes.
The way you are using the Kotlin for loop is much closer to Java's foreach loop for(i : indexes).
I think that because Kotlin is a language that tries to make easy to respect most of the functional programming concepts, it prefers to prohibit that sort of behaviour. Also, a possible problem that your initial code could encount is an OutOfBoundException in the situation where the bytes array has more elements than the data array.

Objective C: Do I have to import arc4random ( )? [closed]

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I'm trying to generate a random number between 0 and 3 by saying
int i = arc4Random() % 3;
but it keeps giving me the warning "implicit declaration of function 'arc4Random' is invalid in c99
Try it without the capital r
int i = arc4random() % 3;
You have a capital "R" in arc4Random. Should be: int i = arc4random % 3;.

What is "fabs" in Objective C? [closed]

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Found this bit of code...
if(fabs([tempPlacemark getCoordinate].latitude-latitude) < latDelta && fabs([tempPlacemark getCoordinate].longitude-longitude)<longDelta )
...
refers to this in Math.h:
extern float fabsf(float);
extern double fabs(double);
extern long double fabsl(long double);
So what am I looking at?
double fabs( double ) - returns the absolute value of the argument
NSLog(#"res: %.f", fabs(10)); //result 10
NSLog(#"res: %.f", fabs(-10)); //result 10
found here.

Why do 2 and 3 equal 2 in VBA? [closed]

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If you evaluate the following in VBA, the output is True:
(2 And 3) = 2
Can someone explain this to me? Thanks!
You have:
2 (base 10) == 10 (base 2)
3 (base 10) == 11 (base 2)
Performing a bitwise AND gives
10 (base 2) == 2 (base 10)
0 = false, everything else is true in VB
I tried to find some link for MS that explained this but I could not.

Why does this code work in Objective-C? I'm getting BAD_ACCESS [closed]

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int RandomSource_next(int bits, double* seed) {
*seed = (((long long) *seed * 0x5DEECE66DLL) + 0xBLL) & ((1LL << 48) - 1);
return (int)((signed long long) *seed >> (48 - bits));
}
I think it got something to do with the address.
Most probably you are passing incorrect address as seed. Maybe you're passing not an address but a value?
The following should work
double seed = 0;
RandomSource_next(48, &seed);
The following should crash
RandomSource_next(48, 0);