Question about return value of STD MAP::INSERT

[ForNow]

Hi I am looking at the documentation for map::insert std::map<Key,T,Compare,Allocator>::insert - cppreference.com[^] seems that when you use two parameters such a key and value it returns a iterator to the inserted or the element that prevented listed below is my code

procpointer->extsymcollector->insert(pair{exsympointer->SYMESDID, *exsympointer });

my code does NOT complie unless I specfify a return value of a pair iterator and bool and the following

std::pair::iterator, bool> ret;
ret = procpointer->extsymcollector->insert(pair{exsympointer->SYMESDID, *exsympointer });

dont understand why ?

[Mircea Neacsu]

You can simplify to:

auto ret = procpointer->extsymcollector->insert({exsympointer->SYMESDID, *exsympointer})

ForNow wrote:

my code does NOT complie

What compiler to you use? what message to you get?

Mircea

[ForNow]

That worked with iterator thanks these overloads drive me crazy 🙂

[ForNow]

when I specify a return of a iterator I get no suitable conversion

map ::iterator extsymiter;

extsympointer = procpointer->extsymcollector->insert({exsympointer->SYMESDID, * exsympointer });

[Mircea Neacsu]

std::map::insert returns a pair. Nothing you can do about that. Your code should look like:

map ::iterator extsymiter;
auto ret = procpointer->extsymcollector->insert({exsympointer->SYMESDID, * exsympointer });
if (ret.second)
extsymiter = ret.first;
else
//map already had an element with same key

If you don't care if the element was there or not, you can just skip the if.

Mircea

[ForNow]

thanks, I tried that BTW I looked at the value of the iterator in storage and seems it prefixes my data with a int with the value of the entry number Thank you again