Databases
StackOverflow2013
Postsdbo
POarray index out of bounds problems
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POarray index out of bounds problems
    primarykey
    data
    text
    <p>So I'm making a biginteger program, and I'm having a problem with adding two arrays that aren't the same length. The problem I'm having is with the add method. If I'm iterating through an array is there any way to test if element is out of bounds. I've tried testing if the element in a is equal to nil, but I still get the exception. Any help would be great thanks. </p> <pre><code> #import &lt;Foundation/Foundation.h&gt; #import "MPInteger.h" @implementation MPInteger { } -(id) initWithString: (NSString *) x { self = [super init]; if (self) { intString = [NSMutableArray array]; for (int i = 0; i &lt; [x length]; i++) { NSString *ch = [x substringWithRange:NSMakeRange(i, 1)]; [intString addObject:ch]; } } return self; } -(NSString *) description { return self.description; } - (MPInteger *) add: (MPInteger *) x { NSMutableArray *a = self-&gt;intString; NSMutableArray *b = x-&gt;intString; NSMutableArray *c = [NSMutableArray array]; NSInteger arrayCount; if (a &lt; b) { arrayCount = [b count]; } else { arrayCount = [a count]; } int num = 10; int carry = 1; NSNumber *total; NSNumber *carrySum; for (int i = 0; i &lt; arrayCount; i++) { if (a[i] == nil) { total = @([b[i] intValue]); [c addObject:total]; } else if (b[i] == nil) { total = @([a[i] intValue]); [c addObject:total]; } else { total = @([a[i] intValue] + [b[i] intValue]); [c addObject:total]; } } for (NSInteger j = [c count]-1; j &gt;=0; j--) { if ([c[j] intValue] &gt;= num) { total = @([c[j] intValue] - num); carrySum = @([c[j-1] intValue] + carry); [c replaceObjectAtIndex:j withObject:total]; [c replaceObjectAtIndex:j-1 withObject: carrySum]; } } NSString *str = [c componentsJoinedByString:@""]; NSLog(@"%@", str); return x; } -(MPInteger *) multiply: (MPInteger *) x { NSMutableArray *a = self-&gt;intString; NSMutableArray *b = x-&gt;intString; NSMutableArray *c = [NSMutableArray array]; NSMutableArray *sum = [NSMutableArray array]; NSNumber *total; NSNumber *carrySum; int num = 10; NSNumber *endZero = 0; NSInteger bottomCount = [b count]-1; while (bottomCount != -1) { for (int i = 0; i &lt; [a count]; i++) { total = @([a[i] intValue] * [[b objectAtIndex:bottomCount] intValue]); if (bottomCount == [b count] -1) { [c addObject:total]; } else { [c replaceObjectAtIndex:i withObject:total]; } } for (NSInteger j = [c count]-1; j&gt;=0; j--) { NSString *carry = [NSString stringWithFormat:@"%d", [c[j] intValue]]; NSString *carry2 = [carry substringToIndex:1]; int carryFinal = [carry2 intValue]; NSString *carry3 = [carry2 stringByAppendingString:@"0"]; int carry4 = [carry3 intValue]; if ([c[j] intValue] &gt;= num) { total = @([c[j] intValue] - carry4); carrySum = @([c[j-1] intValue] + carryFinal); [c replaceObjectAtIndex:j withObject:total]; [c replaceObjectAtIndex:j-1 withObject: carrySum]; } else { if(j == 0) { if (bottomCount == [b count] -1) { bottomCount = bottomCount - 1; NSString *str = [c componentsJoinedByString:@""]; [sum addObject: str]; } else { [c addObject:@([endZero intValue])]; bottomCount = bottomCount - 1; NSString *str = [c componentsJoinedByString:@""]; [sum addObject: str]; } } } } } NSMutableArray *finalSum = [NSMutableArray array]; MPInteger *ele1; MPInteger *ele2; MPInteger *eleSum; NSNumber *endZ= @(0); [finalSum insertObject:endZ atIndex:0]; for (int k = 0; k &lt; [sum count]; k++) { NSString *str= [NSString stringWithFormat:@"%d", [sum[k] intValue]]; NSString *str2 = [NSString stringWithFormat:@"%d", [sum[k+1] intValue]]; ele1 = [[MPInteger alloc] initWithString:str]; ele2 = [[MPInteger alloc] initWithString:str2]; eleSum = [ele1 add: ele2]; NSLog(@"%@", eleSum); } NSLog(@"%@", sum); return self; } </code></pre> <p>Updated this</p> <pre><code> for (int i = 0; i &lt; arrayCount; i++) { if (a[i] == nil) { total = @([b[i] intValue]); [c addObject:total]; } else if (b[i] == nil) { total = @([a[i] intValue]); [c addObject:total]; } else { total = @([a[i] intValue] + [b[i] intValue]); [c addObject:total]; } } </code></pre> <p>has now become:</p> <pre><code>NSMutableArray *c = a.count &gt; b.count ? [a mutableCopy] : [b mutableCopy]; NSArray *shortestArray = a.count &gt; b.count ? b : a; [shortestArray enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(NSNumber *currentNumber, NSUInteger idx, BOOL *stop) { c[idx] = @(currentNumber.integerValue + [c[idx] integerValue]); NSLog(@"%@", c[idx]); }]; </code></pre> <p>What I think I need to do is every index that is in array a and not b or vise versa, is add beginning zeros, but I don't know how to do that.</p> <p>I printed out what it does after each iteration and it gives:</p> <pre><code>2013-09-02 12:31:42.630 Asgn1[42471:303] 5 2013-09-02 12:31:42.632 Asgn1[42471:303] 3 2013-09-02 12:31:42.632 Asgn1[42471:303] 1 And a final answer of: 2013-09-02 12:31:42.633 Asgn1[42471:303] 353 </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. UScourtney
    1. UScourtney
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COPlease reduce the code to the failing part where you merge the arrays.
      singulars
      1. POarray index out of bounds problems
      1. USJanick Bernet
    2. COyou need to check if `i` is less than [array count] for the array in question. You may also want to fill up the difference with zeroes, but not sure if that will be efficient for you
      singulars
      1. POarray index out of bounds problems
      1. USNG.
    3. COI was thinking about doing the zeroes thing, but I didn't know how I would do that.. But I'll try the checking the i against array count.
      singulars
      1. POarray index out of bounds problems
      1. UScourtney
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload