#include <iostream>
#include <vector>
#include <algorithm>
// Define a simple transaction struct
struct Transaction {
int id;
double amount;
};
// Function to find and report the first discrepancy between two transaction logs
void compare_transaction_logs(const std::vector<Transaction>& log_a,
const std::vector<Transaction>& log_b) {
// Use std::ranges::mismatch with projections to compare only the 'id' field of both logs.
// The syntax is: mismatch(range1, range2, pred, proj1, proj2)
// '{}' uses the default comparator (std::ranges::equal_to).
auto result = std::ranges::mismatch(log_a, log_b, {}, &Transaction::id, &Transaction::id);
// result.in1 points to log_a's mismatch point; result.in2 points to log_b's mismatch point.
bool reached_end_a = (result.in1 == log_a.end());
bool reached_end_b = (result.in2 == log_b.end());
if (reached_end_a && reached_end_b) {
std::cout << "Both transaction logs are completely identical.\n";
return;
}
std::cout << "First mismatch found:\n";
if (!reached_end_a) {
std::cout << " Log A -> ID: " << result.in1->id
<< ", Amount: $" << result.in1->amount << "\n";
} else {
std::cout << " Log A reached the end.\n";
}
if (!reached_end_b) {
std::cout << " Log B -> ID: " << result.in2->id
<< ", Amount: $" << result.in2->amount << "\n";
} else {
std::cout << " Log B reached the end.\n";
}
}
int main() {
// Initialize two vectors of transactions
std::vector<Transaction> audit_log_1 = {
{101, 50.0},
{102, 150.0},
{103, 200.0}
};
std::vector<Transaction> audit_log_2 = {
{101, 50.0},
{104, 150.0}, // Mismatching ID here
{103, 200.0}
};
compare_transaction_logs(audit_log_1, audit_log_2);
}
/*
run:
First mismatch found:
Log A -> ID: 102, Amount: $150
Log B -> ID: 104, Amount: $150
*/
