Error Handling in std::unordered_map

1#include <iostream>
2#include <string>
3#include <unordered_map>
4
5int main() {
6  std::unordered_map<std::string, int> map{
7    {"A", 1}, {"B", 2}};
8
9  // Using [] operator
10  if (map.count("C") == 0) {
11    std::cout << "Key 'C' not found\n";
12  } else {
13    int value = map["C"];
14  }
15
16  // Using at() function
17  try {
18    int value = map.at("D");
19  } catch (const std::out_of_range& e) {
20    std::cout << "Key 'D' not found: "
21      << e.what() << '\n';
22  }
23}

1#include <iostream>
2#include <string>
3#include <unordered_map>
4
5int main() {
6  std::unordered_map<std::string, int> map{
7    {"A", 1}, {"B", 2}};
8
9  // Insertion using insert()
10  auto result1 = map.insert({"A", 3});
11  if (!result1.second) {
12    std::cout << "Insertion failed: "
13      "key 'A' already exists\n";
14  }
15
16  // Insertion using emplace()
17  auto result2 = map.emplace("C", 3);
18  if (!result2.second) {
19    std::cout << "Insertion failed: "
20      "key 'C' already exists\n";
21  }
22}

1#include <iostream>
2#include <string>
3#include <unordered_map>
4
5int main() {
6  try {
7    std::unordered_map<std::string, int> map;
8    // Simulate memory allocation failure
9    throw std::bad_alloc();
10  } catch (const std::bad_alloc& e) {
11    std::cout << "Memory allocation failed: "
12      << e.what() << '\n';
13  }
14}