Question

How to search an element with specific value in a map using C++

Answer 1

#include <iostream>  
#include <map>
#include <algorithm>

using std::map;
using std::cout;
using std::endl;
using std::pair;

void printMap(const map<float, float>& mp)
{
	for (auto element : mp) {
		cout << element.first << ": " << element.second << endl;
	}
	cout << endl;
}

int main()
{
	map<float, float> mp = { { 1.1, 3.14 }, { 1.7, 3.87 }, { 1.2 , 2.25 }, { 1.8, 9.0 } };

	printMap(mp);

	auto value = find_if(mp.begin(), mp.end(), [](const pair<float, float>& element) {
		return element.second == 9.0;
	});

	if (value != mp.end()) {
		cout << "value 9.0 exist {"	<< value->first << ": " << value->second << "}" << endl;
	}

	return 0;
}

/*
run:

1.1: 3.14
1.2: 2.25
1.7: 3.87
1.8: 9

value 9.0 exist {1.8: 9}

*/

 

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Answer 2

#include <iostream>  
#include <map>
#include <algorithm>
 
using std::map;
using std::cout;
using std::endl;
using std::pair;
 
void printMap(const map<float, float>& mp)
{
    for (auto element : mp) {
        cout << element.first << ": " << element.second << endl;
    }
    cout << endl;
}
 
int main()
{
    map<float, float> mp = { { 1.1, 3.14 }, { 1.7, 3.87 }, { 1.2 , 2.25 }, { 1.8, 9.99 } };
 
    printMap(mp);
 
    auto value = find_if(mp.begin(), mp.end(), [](const pair<float, float>& element) {
        return element.second == 2.25;
    });
 
    if (value != mp.end()) {
        cout << "value 2.25 exist {"  << value->first << ": " << value->second << "}" << endl;
    }
 
    return 0;
}
 
/*
run:
 
1.1: 3.14
1.2: 2.25
1.7: 3.87
1.8: 9.99
 
value 2.25 exist {1.2: 2.25}
 
*/

 

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Answer 3

#include <iostream>  
#include <map>
#include <algorithm>

using std::map;
using std::cout;
using std::endl;
using std::pair;

void printMap(const map<float, float>& mp)
{
	for (auto element : mp) {
		cout << element.first << ": " << element.second << endl;
	}
	cout << endl;
}

int main()
{
	map<float, float> mp = { { 1.1, 3.14 }, { 1.7, 3.87 }, { 1.2 , 2.25 }, { 1.8, 9.99 } };

	printMap(mp);

	auto value = find_if(mp.begin(), mp.end(), [](const pair<float, float>& element) {
		return element.second == (float)9.99;
	});

	if (value != mp.end()) {
		cout << "value 9.99 exist {"	<< value->first << ": " << value->second << "}" << endl;
	}

	return 0;
}

/*
run:

1.1: 3.14
1.2: 2.25
1.7: 3.87
1.8: 9.99

value 9.99 exist {1.8: 9.99}

*/

 

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