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In this compliant solution, the parameter pos is declared as size_t, which prevents passing the passing of negative arguments (see INT01-CPP. Use rsize_t or size_t for all integer values representing the size of an object).

#include <cstddef>
 
void insert_in_table(int *table, std::size_t tableSize, std::size_t pos, int value) {
  if (pos >= tableSize) {
    // Handle error
    return;
  }
  table[pos] = value;
}

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In this noncompliant code example, a std::vector is used in place of a pointer and size pair. The function performs a range check to ensure that pos does not exceed the upper bound of the container. Because pos is declared as a (signed) long long, this parameter can assume a negative value. On systems where std::vector::size_type is ultimately implemented as an unsigned int (such as with Microsoft Visual Studio 2013), the usual arithmetic conversions applied for the comparison expression will convert the unsigned value to a signed value. If pos has a negative value, this comparison will not fail, resulting in a write outside the bounds of the std::vector object when the negative value is interpreted as a large unsigned value in the indexing operator.

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In this compliant solution, the parameter pos is declared as size_t, which ensures that the comparison expression will fail when a large, positive value (converted from a negative argument) is given:.

#include <vector>
 
void insert_in_table(std::vector<int> &table, std::size_t pos, int value) {
  if (pos >= table.size()) {
    // Handle error
    return;
  }
  table[pos] = value;
}

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In this noncompliant code example, it is possible that the the f_imp() function is given a valid iterator but that the iterator is not within a valid range. For instance, if f() were called with iterators obtained from an empty container, the end() iterator could be the (correct) ending iterator e for a container, and b is an iterator from the same container. However, it is possible that b is not within the valid range of its container. For instance, if the container were empty, b would equal e and be improperly dereferenced.

#include <iterator>
 
template <typename ForwardIterator>
void f_imp(ForwardIterator b, ForwardIterator e, int val, std::forward_iterator_tag) {
  do {
    *b++ = val;
  } while (b != e);
}

template <typename ForwardIterator>
void f(ForwardIterator b, ForwardIterator e, int val) {
  typename std::iterator_traits<ForwardIterator>::iterator_category cat;
  f_imp(b, e, val, cat);
}

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This compliant solution tests for iterator validity before attempting to dereference the forward iterator: b.

#include <iterator>
 
template <typename ForwardIterator>
void f_imp(ForwardIterator b, ForwardIterator e, int val, std::forward_iterator_tag) {
  while (b != e) {
    *b++ = val;
  }
}

template <typename ForwardIterator>
void f(ForwardIterator b, ForwardIterator e, int val) {
  typename std::iterator_traits<ForwardIterator>::iterator_category cat;
  f_imp(b, e, val, cat);
}

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Using an invalid array or container index can result in an arbitrary memory overwrite or abnormal program termination.

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Bibliography

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