From f871b625ee94fe721c60e3200785310d653393f8 Mon Sep 17 00:00:00 2001
From: Philip Top <phlptp@gmail.com>
Date: Tue, 11 Mar 2025 07:08:38 -0700
Subject: [PATCH] Float parsing negative (#1140)

Fixes #1139
Fix a bug relating to parsing negative floating point values with no
zero before decimal point in a context where an option could be
possible.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 include/CLI/impl/App_inl.hpp |  4 +++-
 tests/OptionTypeTest.cpp     | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/include/CLI/impl/App_inl.hpp b/include/CLI/impl/App_inl.hpp
index 69eccf72..10e0a568 100644
--- a/include/CLI/impl/App_inl.hpp
+++ b/include/CLI/impl/App_inl.hpp
@@ -1090,7 +1090,9 @@ CLI11_NODISCARD CLI11_INLINE detail::Classifier App::_recognize(const std::strin
     if(detail::split_long(current, dummy1, dummy2))
         return detail::Classifier::LONG;
     if(detail::split_short(current, dummy1, dummy2)) {
-        if(dummy1[0] >= '0' && dummy1[0] <= '9') {
+        if((dummy1[0] >= '0' && dummy1[0] <= '9') ||
+           (dummy1[0] == '.' && !dummy2.empty() && (dummy2[0] >= '0' && dummy2[0] <= '9'))) {
+            // it looks like a number but check if it could be an option
             if(get_option_no_throw(std::string{'-', dummy1[0]}) == nullptr) {
                 return detail::Classifier::NONE;
             }
diff --git a/tests/OptionTypeTest.cpp b/tests/OptionTypeTest.cpp
index c1193bdf..d89a1357 100644
--- a/tests/OptionTypeTest.cpp
+++ b/tests/OptionTypeTest.cpp
@@ -232,6 +232,9 @@ static const std::map<std::string, double> testValuesDouble{
     {"-3.14159  ", -3.14159},
     {"+1.0", 1.0},
     {"-0.01", -0.01},
+    {"-.01", -0.01},
+    {"-.3251", -0.3251},
+    {"+.3251", 0.3251},
     {"5e22", 5e22},
     {" 5e22", 5e22},
     {" 5e22  ", 5e22},
@@ -822,6 +825,28 @@ TEST_CASE_METHOD(TApp, "floatPair", "[optiontype]") {
     CHECK(2.7f == Approx(custom_opt.second));
 }
 
+// now with tuple support this is possible
+TEST_CASE_METHOD(TApp, "doubleVector", "[optiontype]") {
+
+    std::vector<double> custom_opt;
+
+    app.add_option("--fp", custom_opt);
+
+    args = {"--fp", "12.7", "1.5"};
+    run();
+    CHECK(12.7 == Approx(custom_opt[0]));
+    CHECK(1.5 == Approx(custom_opt[1]));
+    args = {"--fp", "12.7", "-.5"};
+    run();
+    CHECK(12.7 == Approx(custom_opt[0]));
+    CHECK(-0.5 == Approx(custom_opt[1]));
+
+    args = {"--fp", "-.7", "+.5"};
+    run();
+    CHECK(-0.7 == Approx(custom_opt[0]));
+    CHECK(0.5 == Approx(custom_opt[1]));
+}
+
 // now with independent type sizes and expected this is possible
 TEST_CASE_METHOD(TApp, "vectorPair", "[optiontype]") {