From cppreference.com
Defined in header
template<classT,classAlloc,classU>std::list<T,Alloc>::size_typeerase(std::list<T,Alloc>&c,constU&value); (1)(since C++20)
(until C++26)template<classT,classAlloc,classU=T>std::list<T,Alloc>::size_typeerase(std::list<T,Alloc>&c,constU&value);(since C++26)template<classT,classAlloc,classPred>std::list<T,Alloc>::size_typeerase_if(std::list<T,Alloc>&c,Predpred); (2) (since C++20)1) Erases all elements that compare equal to value from the container. Equivalent to returnc.remove_if([&](constauto&elem)->bool{returnelem==value;});.
2) Erases all elements that satisfy the predicate pred from the container. Equivalent to returnc.remove_if(pred);.
Parameters
c - container from which to erase value - value to be removed pred - unary predicate which returns true if the element should be erased. The expression pred(v) must be convertible to bool for every argument v of type (possibly const) T, regardless of
, and must not modify v. Thus, a parameter type of T&is not allowed, nor is T unless for T a move is equivalent to a copy(since C++11).
Return value
The number of erased elements.
Complexity
Linear.
Notes
Unlike
, erase accepts heterogeneous types and does not force a conversion to the container's value type before invoking the == operator.
macroValueStdFeature
__cpp_lib_algorithm_default_value_type
(C++26)
for algorithm (
)Example
Run this code
#include<complex>#include<numeric>#include<print>#include<list>template<typenameT>structstd::formatter<std::complex<T>,char>{template<classParseContext>constexprParseContext::iteratorparse(ParseContext&ctx){returnctx.begin();}template<classFmtContext>FmtContext::iteratorformat(constauto&s,FmtContext&ctx)const{autoout{std::format("({},{})",s.real(),s.imag())};returnstd::ranges::copy(std::move(out),ctx.out()).out;}};intmain(){std::list<char>cnt(10);std::iota(cnt.begin(),cnt.end(),'0');std::println("Initially, cnt = {}",cnt);std::erase(cnt,'3');std::println("After erase '3', cnt = {}",cnt);autoerased=std::erase_if(cnt,[](charx){return(x-'0')%2==0;});std::println("After erase all even numbers, cnt = {}",cnt);std::println("Erased even numbers: {}",erased);std::list<std::complex<double>>nums{{2,2},{4,2},{4,8},{4,2}};#ifdef __cpp_lib_algorithm_default_value_typestd::erase(nums,{4,2});#elsestd::erase(nums,std::complex<double>{4,2});#endifstd::println("After erase {{4, 2}}, nums = {}",nums);}Output:
Initially, cnt = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] After erase '3', cnt = [0, 1, 2, 4, 5, 6, 7, 8, 9] After erase all even numbers, cnt = [1, 5, 7, 9] Erased even numbers: 5 After erase {4, 2}, nums = [(2,2), (4,8)] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++20 the return type of the lambda predicate used
was deduced from predicate arguments the return type is
explicitly specified as boolSee also