add an example of finding close matches

examples/CMakeLists.txt

@@ -250,6 +250,8 @@ set_property(TEST retired_retired_test3 PROPERTY PASS_REGULAR_EXPRESSION "WARNIN
 
 set_property(TEST retired_deprecated PROPERTY PASS_REGULAR_EXPRESSION "deprecated.*not_deprecated")
 
+add_cli_exe(close_match close_match.cpp)
+
 #--------------------------------------------
 add_cli_exe(custom_parse custom_parse.cpp)
 add_test(NAME cp_test COMMAND custom_parse --dv 1.7)

examples/close_match.cpp

@@ -0,0 +1,107 @@
+// Copyright (c) 2017-2025, University of Cincinnati, developed by Henry Schreiner
+// under NSF AWARD 1414736 and by the respective contributors.
+// All rights reserved.
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code inspired by discussion from https://github.com/CLIUtils/CLI11/issues/1149
+
+#include <CLI/CLI.hpp>
+#include <iostream>
+#include <string>
+#include <vector>
+#include <limits>
+
+// Levenshtein distance function code generated by chatgpt
+int levenshteinDistance(const std::string& s1, const std::string& s2) {
+    size_t len1 = s1.size(), len2 = s2.size();
+    std::vector<std::vector<int>> dp(len1 + 1, std::vector<int>(len2 + 1));
+
+    for (size_t i = 0; i <= len1; ++i) dp[i][0] = i;
+    for (size_t j = 0; j <= len2; ++j) dp[0][j] = j;
+
+    for (size_t i = 1; i <= len1; ++i) {
+        for (size_t j = 1; j <= len2; ++j) {
+            int cost = (s1[i - 1] == s2[j - 1]) ? 0 : 1;
+            dp[i][j] = std::min({ 
+                dp[i - 1][j] + 1,     // deletion
+                dp[i][j - 1] + 1,     // insertion
+                dp[i - 1][j - 1] + cost // substitution
+                });
+        }
+    }
+
+    return dp[len1][len2];
+}
+
+// Finds the closest string from a list
+std::pair<std::string,int> findClosestMatch(const std::string& input, const std::vector<std::string>& candidates) {
+    std::string closest;
+    int minDistance = std::numeric_limits<int>::max();
+
+    for (const auto& candidate : candidates) {
+        int distance = levenshteinDistance(input, candidate);
+        if (distance < minDistance) {
+            minDistance = distance;
+            closest = candidate;
+        }
+    }
+
+    return { closest,minDistance };
+}
+
+/** This example demonstrates the use of `prefix_command` on a subcommand
+to capture all subsequent arguments along with an alias to make it appear as a regular options.
+
+All the values after the "sub" or "--sub" are available in the remaining() method.
+*/
+int main(int argc, const char *argv[]) {
+
+    int value{0};
+    CLI::App app{"cose string App"};
+    app.add_option("-v", value, "value");
+
+    app.add_subcommand("install", "");
+    app.add_subcommand("upgrade","");
+    app.add_subcommand("remove","");
+    app.add_subcommand("test","");
+    app.allow_extras(true);
+
+    app.parse_complete_callback([&app]() {
+        auto extras = app.remaining();
+        if (extras.empty())
+        {
+            return;
+        }
+        auto subs = app.get_subcommands(nullptr);
+        std::vector<std::string> list;
+        for (const auto* sub : subs) {
+            if (!sub->get_name().empty())
+            {
+                list.push_back(sub->get_name());
+            }
+            auto aliases = sub->get_aliases();
+            if (!aliases.empty())
+            {
+                list.insert(list.end(), aliases.begin(), aliases.end());
+            }
+
+        }
+        for (auto& extra : extras)
+        {
+            if (extra.front() != '-')
+            {
+                auto closest = findClosestMatch(extra,list);
+                if (closest.second <= 3)
+                {
+                    std::cout<<"unmatched commands "<<extra<<", closest match is "<<closest.first<<"\n";
+                }
+            }
+        }
+        
+        }
+        );
+    CLI11_PARSE(app, argc, argv);
+    return 0;
+    
+}