Data Structure: Logical error in a linear search program - search

Question

The following function is supposed to execute a linear search.
int linsearch(T arr[],int size,T target)
{
int begin;
int loc;
bool found;
for(begin=0;begin<size&&target!=arr[begin];begin++);
loc = begin;
if(target==arr[loc])
found = loc;
else
found = -1;
return found;
}
However, not matter what I search, I always get 1 as the output. This happens when the element is in or out of the array. Please help.

Answer 1

bool found;
:
return found;
Boolean values are generally limited to true/false, which is often repesented as 1/0. There's a good chance that placing a non-zero value into a bool will coerce it to 1.
If you want to return the index where it was found, you should probably use an int:
int found;
However, even if you make that change it won't work:
int linsearch(T arr[],int size,T target)
{
int begin;
int loc;
int found; // <<-- changed this
for(begin=0;begin<size&&target!=arr[begin];begin++);
loc = begin;
if(target==arr[loc])
found = loc;
else
found = -1;
return found;
}
That's because, in the event you don't find the item, begin (and loc since you set it to begin) is left as size so you're checking beyond the ends of the array with arr[loc].
You really should check for that condition properly immediately after the loop, with something like (removing loc altogether since it's unnecessary):
if (begin == size)
found = -1;
else
found = begin;
In any case, your code could probably be substantially less verbose:
int linsearch (T arr[], int size, T target)
{
int loc;
for (loc = 0; loc < size; loc++)
if (target == arr[loc])
return loc;
return -1;
}