C++ vector<string>::iterator - 如何找到元素的位置
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vector<string>::iterator - how to find position of an element
提问by user2754070
I am using the following code to find a string in an std::vectorof stringtype. But how to return the position of particular element?
我使用下面的代码找到一个字符串std::vector的string类型。但是如何返回特定元素的位置？
Code:
代码：
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main() {
vector<string> vec;
vector<string>::iterator it;
vec.push_back("H");
vec.push_back("i");
vec.push_back("g");
vec.push_back("h");
vec.push_back("l");
vec.push_back("a");
vec.push_back("n");
vec.push_back("d");
vec.push_back("e");
vec.push_back("r");
it=find(vec.begin(),vec.end(),"r");
//it++;
if(it!=vec.end()){
cout<<"FOUND AT : "<<*it<<endl;
}
else{
cout<<"NOT FOUND"<<endl;
}
return 0;
}
Output:
输出：
FOUND AT : r
FOUND AT : r
Expected Output:
预期输出：
FOUND AT : 9
FOUND AT : 9
回答by juanchopanza
You can use std::distancefor that:
你可以使用std::distance：
auto pos = std::distance(vec.begin(), it);
For an std::vector::iterator, you can also use arithmetic:
对于std::vector::iterator，您还可以使用算术：
auto pos = it - vec.begin();
回答by P0W
Use following :
使用以下：
if(it != vec.end())
std::cout<< "Found At :" << (it-vec.begin()) ;
回答by Pingakshya Goswami
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main() {
vector<string> vec;
vector<string>::iterator it;
vec.push_back("H");
vec.push_back("i");
vec.push_back("g");
vec.push_back("h");
vec.push_back("l");
vec.push_back("a");
vec.push_back("n");
vec.push_back("d");
vec.push_back("e");
vec.push_back("r");
it=find(vec.begin(),vec.end(),"a");
//it++;
int pos = distance(vec.begin(), it);
if(it!=vec.end()){
cout<<"FOUND "<< *it<<" at position: "<<pos<<endl;
}
else{
cout<<"NOT FOUND"<<endl;
}
return 0;
回答by keep_smiling
Use this statement:
使用这个语句：
it = find(vec.begin(), vec.end(), "r") - vec.begin();
