Independent Researcher
Question
Asked 28 January 2011
Negative indices in C
Hello Friends,
Anyone please explain to me what happens when i supply negative index in C array. I got garbage value when i tried it.
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All Answers (11)
Jiwaji University
Array indices start from 0 in C++ , I guess C too..
try to convert negative indices into positive..
Array[(i* -1)] , where i :negative index..
University of Oklahoma
An array in most programming languages is just a contiguous area of addressable storage and the language, say C, Rexx, NetRexx/JAVA keeps track of each element's 'address' starting from zero. When you tell C to address a negative amount it obliges with whatever garbage was in storage preceding the array's storage area. Rexx and NetRexx are not so brutal. I'm not sure what JAVA does; In general, it follows C.
1 Recommendation
University of Oklahoma
No matter what the language, best practice is to check the array index before it is used to make sure it is within logical bounds.
Robert L Hamilton, Engineer
Richardson, Texas USA
if y'u are trying to get negative value the program itself is vague, or absurd, because negative statements are considered as junk statements in programming languages, only positive statements are considered in p languages, so y'ur question is vague.
Jawaharlal Nehru Technological University, Hyderabad
index of an array, actually points to a position relative to the base address of the array(.i.e address of a[0]). Therefore a[3] is a location 3 positions after a[0] or is equivalent to:
*p=&a[0];
*p++; *p++; *p++;
hence a[-2] implies
*p--; *p--; *p--;
which is still a memory location(provided it exists) nevertheless (and can therefore show the value at the location) , but is not a part of your logical array,a
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