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| Unordered associative | ||||
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| Iterator invalidation | ||||
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Defined in header <map> | ||
| (since C++20) (constexpr since C++26) | ||
Erases all elements that satisfy the predicatepred fromc.
Equivalent to
auto old_size= c.size();for(auto first= c.begin(), last= c.end(); first!= last;){if(pred(*first)) first= c.erase(first);else++first;}return old_size- c.size();
Contents |
| c | - | container from which to erase |
| pred | - | predicate that returnstrue if the element should be erased |
The number of erased elements.
Linear.
#include <iostream>#include <map> void println(auto rem,constauto& container){std::cout<< rem<<'{';for(char sep[]{0,' ',0};constauto&[key, value]: container)std::cout<< sep<<'{'<< key<<", "<< value<<'}',*sep=',';std::cout<<"}\n";} int main(){std::map<int,char> data{{1,'a'},{2,'b'},{3,'c'},{4,'d'},{5,'e'},{4,'f'},{5,'g'},{5,'g'},}; println("Original:\n", data); constauto count=std::erase_if(data,[](constauto& item){constauto&[key, value]= item;return(key&1)==1;}); println("Erase items with odd keys:\n", data);std::cout<< count<<" items removed.\n";}
Output:
Original:{{1, a}, {2, b}, {3, c}, {4, d}, {5, e}}Erase items with odd keys:{{2, b}, {4, d}}3 items removed.| removes elements satisfying specific criteria (function template)[edit] | |
(C++20)(C++20) | removes elements satisfying specific criteria (algorithm function object)[edit] |
