c ++ find_if lambda [英] c++ find_if lambda
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问题描述
下面的代码有什么问题?如果结构体的第一个memebers == 0,它应该在结构体列表中找到一个元素。编译器会提示lambda参数不是Predicate类型。
#include< iostream>
#include< stdint.h>
#include< fstream>
#include< list>
#include< algorithm>
struct S
{
int S1;
int S2;
};
using namespace std;
int main()
{
list< S> l;
S s1;
s1.S1 = 0;
s1.S2 = 0;
S s2;
s2.S1 = 1;
s2.S2 = 1;
l.push_back(s2);
l.push_back(s1);
list< S> :: iterator it = find_if(l.begin(),l.end(),[](S s){return s.S1 == 0;});在VS2012上,代码可以正常工作,但是这个代码可以正常工作,只有一个建议,通过引用传递对象而不是传递值: list< S> :: iterator it = find_if .begin(),l.end(),[](const S& s){return s.S1 == 0;});
What is wrong with the code below? It is supposed to find an element in the list of structs if the first of the struct's memebers == 0. The compiler complains about the lambda argument not being of type Predicate.
#include <iostream>
#include <stdint.h>
#include <fstream>
#include <list>
#include <algorithm>
struct S
{
int S1;
int S2;
};
using namespace std;
int main()
{
list<S> l;
S s1;
s1.S1 = 0;
s1.S2 = 0;
S s2;
s2.S1 = 1;
s2.S2 = 1;
l.push_back(s2);
l.push_back(s1);
list<S>::iterator it = find_if(l.begin(), l.end(), [] (S s) { return s.S1 == 0; } );
}
解决方案 Code works fine on VS2012, just one recommendation, pass object by reference instead of pass by value:
list<S>::iterator it = find_if(l.begin(), l.end(), [] (const S& s) { return s.S1 == 0; } );
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