C++ - segmentation fault on second binary search - c++

Question

I have a class ledger, whose instances are supposed to store instances of a member class company in two vectors combyID and combyname, sorted by two different criteria - ID and name (both are strings). The vectors start out empty, so instead of sorting them after each new addition of an instance of the member class, a customized binary search methods binsID and binsName search the vectors for the element to be added and if the element isn't found, it is inserted in the vectors. The insert() position is defined by the idx value, modified by the binary search method.
The problem lies within the method NewCo, which calls both binary search methods and eventually inserts the element to the vectors. When the program is run with more than just one NewCo call in the main function, Segmentation fault (core dumped) error is given. The error doesn't appear either if the binsID method isn't called or the insert() isn't called on combyID (omitting the insertion to that vector). I am posting both the code and the valgrind analysis.
The code:
#include <cstdlib>
#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
using namespace std;
class ledger
{
public:
bool NewCo (string name, string ID)
{
unsigned int idx_id = 0, idx_name = 0;
bool found1 = binsID(combyID, idx_id, ID); //line 14
bool found2 = binsName(combyname, idx_name, name);
if (found1 == false && found2 == false)
{
company co;
co.co_name = name;
co.co_id = ID;
combyID.insert(combyID.begin() + idx_id, co);
combyname.insert(combyname.begin() + idx_name, co);
return 1;
}
return 0;
}
private:
class company
{
public:
string co_name;
string co_id;
};
vector <company> combyID;
vector <company> combyname;
bool binsName(vector <company> vek, unsigned int & idx, string val)
{
if (vek.size() == 0) return false;
unsigned int begin = 0, end = vek.size() - 1, mid;
while(begin <= end)
{
mid = (begin + end) / 2;
idx = mid;
if (vek[mid].co_name == val)
{
idx = mid;
return true;
}
else if (val < vek[mid].co_name)
end = mid - 1;
else
begin = mid + 1;
}
if (vek[idx].co_name < val) idx++;
return false;
}
bool binsID(vector <company> vek, unsigned int & idx, string val)
{
if (vek.size() == 0) return false;
unsigned int begin = 0, end = vek.size() - 1, mid;
while(begin <= end)
{
mid = (begin + end) / 2;
idx = mid;
if (vek[mid].co_id == val) //line 66
{
idx = mid;
return true;
}
else if (val < vek[mid].co_id)
end = mid - 1;
else
begin = mid + 1;
}
if (vek[idx].co_id < val) idx++;
return false;
}
};
int main ( void )
{
ledger b1;
b1.NewCo( "ABC", "123.456.789" );
b1.NewCo( "DEF", "123.456" ); //line 85
return 0;
}
Valgrind:
==6775== Command: ./a.out -g
==6775==
==6775== Invalid read of size 8
==6775== at 0x4F597B0: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::size() const (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==6775== by 0x401C2A: __gnu_cxx::__enable_if<std::__is_char<char>::__value, bool>::__type std::operator==<char>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:4913)
==6775== by 0x40177B: ledger::binsID(std::vector<ledger::company, std::allocator<ledger::company> >, unsigned int&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (main.cpp:66)
==6775== by 0x40138B: ledger::NewCo(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (main.cpp:14)
==6775== by 0x40109E: main (main.cpp:85)
==6775== Address 0x2005ab5d68 is not stack'd, malloc'd or (recently) free'd
==6775==
==6775==
==6775== Process terminating with default action of signal 11 (SIGSEGV)
==6775== Access not within mapped region at address 0x2005AB5D68
==6775== at 0x4F597B0: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::size() const (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==6775== by 0x401C2A: __gnu_cxx::__enable_if<std::__is_char<char>::__value, bool>::__type std::operator==<char>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:4913)
==6775== by 0x40177B: ledger::binsID(std::vector<ledger::company, std::allocator<ledger::company> >, unsigned int&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (main.cpp:66)
==6775== by 0x40138B: ledger::NewCo(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (main.cpp:14)
==6775== by 0x40109E: main (main.cpp:85)
==6775== If you believe this happened as a result of a stack
==6775== overflow in your program's main thread (unlikely but
==6775== possible), you can try to increase the size of the
==6775== main thread stack using the --main-stacksize= flag.
==6775== The main thread stack size used in this run was 8388608.
==6775==
==6775== HEAP SUMMARY:
==6775== in use at exit: 72,896 bytes in 4 blocks
==6775== total heap usage: 4 allocs, 0 frees, 72,896 bytes allocated
==6775==
==6775== LEAK SUMMARY:
==6775== definitely lost: 0 bytes in 0 blocks
==6775== indirectly lost: 0 bytes in 0 blocks
==6775== possibly lost: 0 bytes in 0 blocks
==6775== still reachable: 72,896 bytes in 4 blocks
==6775== suppressed: 0 bytes in 0 blocks
==6775== Rerun with --leak-check=full to see details of leaked memory
==6775==
==6775== For counts of detected and suppressed errors, rerun with: -v
==6775== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)

Answer 1

You'll want to review your algorithms in both binsName() and binsID() methods.
For your second pass, the statement:
end = mid - 1;
is producing an end value of -1 (or in this case, UINT_MAX since you're using unsigned integers) as the value of mid is 0.