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POPointer is Affected on Function Call Where it Shouldn't Be
primarykey
Id
4990178
data
AcceptedAnswerId
0
AnswerCount
5
ClosedDate
CommentCount
5
CommunityOwnedDate
CreationDate
2011-02-14T08:41:21.957
FavoriteCount
0
LastActivityDate
2011-02-14T15:54:35.187
LastEditDate
2011-02-14T09:21:04.010
LastEditorUserId
83386
OwnerUserId
83386
ParentId
0
PostTypeId
1
Score
2
ViewCount
102
LastEditorDisplayName
text
Body
I am calling the function below, which calculates a value given in the passed in variables. However, when the function (<code>calculate_distance</code>) runs, the data contained in the variable (<code>loc_ptr</code>) that is passed into the function seems to change. I have stepped through the code to find that the variable <code>loc_ptr</code> is affected on the function call, rather than inside the function itself. The function is being called in a while loop. The first iteration of the while loop calculates correctly, it is only on subsequent iterations that the problem seems to occur. _Note: location is a typedef'ed struct containing char *name, double latitude, double longitude. <code>options</code> is an array of doubles._ <pre><code>double calculate_distance(location from, location to) { return to.latitude - from.latitude; } main() { location current_location = {"Plymouth", 50.378565, -4.134339}; location locations[3] = {{"Padstow", 50.5384, -4.9378}, {"Newquay", 50.412, -5.0757}, {"Boscastle", 50.684, -4.6929}}; // create a pointer to an array of locations. location* loc_ptr; loc_ptr = &locations[0]; double options[3]; int i = 0; int position = 3; while (i < position) { // calculate the distance between the current and other locations options[position] = calculate_distance(current_location, loc_ptr[position]); position--; } // handle the rest of the algorithm } </code></pre> Note: The code is part of a larger algorithm, it's cut short as it would be quite long. After the while loop finishes, the <code>loc_ptr</code> array is rebuilt to remove one of the elements.
Tags
<c><function><pointers>
Title
Pointer is Affected on Function Call Where it Shouldn't Be
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1. This table or related slice is empty.
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1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USnickcharlton
UserOwnerUserId
1. USnickcharlton
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1. This table or related slice is empty.
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1. PO
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 PTAnswer
2. PO
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 PTAnswer
3. PO
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 PTAnswer
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1. VO
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 POPointer is Affected on Function Call Where it Shouldn't Be
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2. VO
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 POPointer is Affected on Function Call Where it Shouldn't Be
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 This table or related slice is empty.
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