What Happens When Erasing a Map Element During Iteration in C ?

What Happens When You Call erase() on a Map Element While Iterating from Begin to End?

In C 03, erasing an element in a map invalidates the iterator pointing to that element. However, in C 11 and later, the erase method returns the next iterator, allowing for safe iteration after element removal.

Solution for C 03

In C 03, to ensure safe iteration after removing elements from a map, update your code to use the iterator returned by map::erase() and perform post-increment on the iterator after calling erase().

map<string, SerialdMsg::SerialFunction_t>::iterator pm_it = port_map.begin();<br>while(pm_it != port_map.end())<br>{</p>
<pre class="brush:php;toolbar:false">if (pm_it->second == delete_this_id)
{
    port_map.erase(pm_it++);  // Use iterator.
                              // Note the post increment.
                              // Increments the iterator but returns the
                              // original value for use by erase 
}
else
{
    ++pm_it;           // Can use pre-increment in this case
                       // To make sure you have the efficient version
}

}

Solution for C 11 and Later

In C 11 and later, erase() returns the next iterator, making it safe to iterate and remove elements simultaneously using the following syntax:

<br>auto pm_it = port_map.begin();<br>while(pm_it != port_map.end())<br>{</p>
<pre class="brush:php;toolbar:false">if (pm_it->second == delete_this_id)
{
    pm_it = port_map.erase(pm_it);
}
else
{
    ++pm_it;
}

}

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