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• both iterators refer into the same container,
• the iterator representing the start of the range precedes the iterator representing the end of the range,
• the elements iterated over do not have unspecified values, and
• the iterators are not invalidated, in conformance with CTR32CTR51-CPP. Use valid references, pointers, and iterators to reference elements of a container.

Accessing two iterators which do not refer into the same container or accessing invalidated iterators results in undefined behavior.

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#include <algorithm>
#include <iostream>
#include <vector>
 
void f(const std::vector<int> &C) {
  std::for_each(C.end(), C.begin(), [](int I) { std::cout << I; });

}

Invalid iterator ranges can also result from comparison functions that return true for equal values. See CTR40-CPP. Provide a valid ordering predicate for more information about comparators.

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Related Guidelines

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