fix most (all?) the places where string<->double conversions are performed

strod / stod / to_string and all related friends are dependant on current locale for how they format a number

include/xlnt/utils/numeric.hpp

@@ -129,10 +129,12 @@ class number_serialiser
 
 public:
     explicit number_serialiser()
-        : should_convert_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+        : should_convert_comma(localeconv()->decimal_point[0] == ',')
     {
     }
 
+    // for printing to file.
+    // This matches the output format of excel irrespective of current locale
     std::string serialise(double d) const
     {
         char buf[30];
@@ -144,29 +146,43 @@ public:
         return std::string(buf, static_cast<size_t>(len));
     }
 
-    double deserialise(std::string &s) const noexcept
+    // replacement for std::to_string / s*printf("%f", ...)
+    // behaves same irrespective of locale
+    std::string serialise_short(double d) const
     {
-        assert(!s.empty());
+        char buf[30];
+        int len = snprintf(buf, sizeof(buf), "%f", d);
         if (should_convert_comma)
         {
-            // s.data() doesn't have a non-const overload until c++17, hence this little dance
+            convert_comma_to_pt(buf, len);
-            convert_pt_to_comma(&s[0], s.size());
         }
-        return strtod(s.c_str(), nullptr);
+        return std::string(buf, static_cast<size_t>(len));
     }
 
-    double deserialise(const std::string &s) const
+    double deserialise(const std::string &s, ptrdiff_t *len_converted) const
     {
         assert(!s.empty());
+        assert(len_converted != nullptr);
+        char *end_of_convert;
         if (!should_convert_comma)
         {
-            return strtod(s.c_str(), nullptr);
+            double d = strtod(s.c_str(), &end_of_convert);
+            *len_converted = end_of_convert - s.c_str();
+            return d;
         }
         char buf[30];
         assert(s.size() < sizeof(buf));
         auto copy_end = std::copy(s.begin(), s.end(), buf);
         convert_pt_to_comma(buf, static_cast<size_t>(copy_end - buf));
-        return strtod(buf, nullptr);
+        double d = strtod(buf, &end_of_convert);
+        *len_converted = end_of_convert - buf;
+        return d;
+    }
+
+    double deserialise(const std::string &s) const
+    {
+        ptrdiff_t ignore;
+        return deserialise(s, &ignore);
     }
 };
 

source/cell/cell.cpp

@@ -57,15 +57,16 @@
 #include <detail/implementations/hyperlink_impl.hpp>
 #include <detail/implementations/stylesheet.hpp>
 #include <detail/implementations/worksheet_impl.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace {
 
 std::pair<bool, double> cast_numeric(const std::string &s)
 {
-    auto str_end = static_cast<char *>(nullptr);
+    xlnt::detail::number_serialiser ser;
-    auto result = std::strtod(s.c_str(), &str_end);
+    ptrdiff_t len_convert;
-
+    double result = ser.deserialise(s, &len_convert);
-    return (str_end != s.c_str() + s.size())
+    return (len_convert != static_cast<ptrdiff_t>(s.size()))
         ? std::make_pair(false, 0.0)
         : std::make_pair(true, result);
 }
@@ -108,7 +109,7 @@ std::pair<bool, xlnt::time> cast_time(const std::string &s)
     }
 
     std::vector<double> numeric_components;
-
+    xlnt::detail::number_serialiser ser;
     for (auto component : time_components)
     {
         if (component.empty() || (component.substr(0, component.find('.')).size() > 2))
@@ -123,9 +124,7 @@ std::pair<bool, xlnt::time> cast_time(const std::string &s)
                 return {false, result};
             }
         }
-
+        auto numeric = ser.deserialise(component);
-        auto without_leading_zero = component.front() == '0' ? component.substr(1) : component;
-        auto numeric = std::stod(without_leading_zero);
 
         numeric_components.push_back(numeric);
     }

source/detail/number_format/number_formatter.cpp

@@ -26,6 +26,7 @@
 #include <cmath>
 
 #include <xlnt/utils/exceptions.hpp>
+#include <xlnt/utils/numeric.hpp>
 #include <detail/default_case.hpp>
 #include <detail/number_format/number_formatter.hpp>
 
@@ -622,7 +623,8 @@ void number_format_parser::parse()
                 value = token.string.substr(1);
             }
 
-            section.condition.value = std::stod(value);
+            detail::number_serialiser ser;
+            section.condition.value = ser.deserialise(value);
             break;
         }
 
@@ -1565,19 +1567,7 @@ std::string number_formatter::fill_placeholders(const format_placeholders &p, do
     if (p.type == format_placeholders::placeholders_type::general
         || p.type == format_placeholders::placeholders_type::text)
     {
-        result = std::to_string(number);
+        return serialiser_.serialise_short(number);
-
-        while (result.back() == '0')
-        {
-            result.pop_back();
-        }
-
-        if (result.back() == '.')
-        {
-            result.pop_back();
-        }
-
-        return result;
     }
 
     if (p.percentage)
@@ -1636,21 +1626,22 @@ std::string number_formatter::fill_placeholders(const format_placeholders &p, do
         auto fractional_part = number - integer_part;
         result = std::fabs(fractional_part) < std::numeric_limits<double>::min()
             ? std::string(".")
-            : std::to_string(fractional_part).substr(1);
+            : serialiser_.serialise_short(fractional_part).substr(1);
 
         while (result.back() == '0' || result.size() > (p.num_zeros + p.num_optionals + p.num_spaces + 1))
         {
             result.pop_back();
         }
 
-        while (result.size() < p.num_zeros + 1)
+        
+        if (result.size() < p.num_zeros + 1)
         {
-            result.push_back('0');
+            result.resize(p.num_zeros + 1, '0');
         }
 
-        while (result.size() < p.num_zeros + p.num_optionals + p.num_spaces + 1)
+        if (result.size() < p.num_zeros + p.num_optionals + p.num_spaces + 1)
         {
-            result.push_back(' ');
+            result.resize(p.num_zeros + p.num_optionals + p.num_spaces + 1, ' ');
         }
 
         if (p.percentage)
@@ -1689,13 +1680,7 @@ std::string number_formatter::fill_scientific_placeholders(const format_placehol
         integer_string = std::string(integer_part.num_zeros + integer_part.num_optionals, '0');
     }
 
-    std::string fractional_string = std::to_string(fraction).substr(1);
+    std::string fractional_string = serialiser_.serialise_short(fraction).substr(1, fractional_part.num_zeros + fractional_part.num_optionals + 1);
-
-    while (fractional_string.size() > fractional_part.num_zeros + fractional_part.num_optionals + 1)
-    {
-        fractional_string.pop_back();
-    }
-
     std::string exponent_string = std::to_string(logarithm);
 
     while (exponent_string.size() < fractional_part.num_zeros)

source/detail/number_format/number_formatter.hpp

@@ -28,6 +28,7 @@
 #include <vector>
 
 #include <xlnt/utils/datetime.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace xlnt {
 namespace detail {
@@ -691,6 +692,7 @@ private:
     number_format_parser parser_;
     std::vector<format_code> format_;
     xlnt::calendar calendar_;
+    xlnt::detail::number_serialiser serialiser_;
 };
 
 } // namespace detail

source/detail/serialization/xlsx_producer.cpp

@@ -2813,33 +2813,12 @@ void xlsx_producer::write_worksheet(const relationship &rel)
     {
         write_start_element(xmlns, "pageMargins");
 
-        // TODO: there must be a better way to do this
+        write_attribute("left", ws.page_margins().left());
-        auto remove_trailing_zeros = [](const std::string &n) -> std::string {
+        write_attribute("right", ws.page_margins().right());
-            auto decimal = n.find('.');
+        write_attribute("top", ws.page_margins().top());
-
+        write_attribute("bottom", ws.page_margins().bottom());
-            if (decimal == std::string::npos) return n;
+        write_attribute("header", ws.page_margins().header());
-
+        write_attribute("footer", ws.page_margins().footer());
-            auto index = n.size() - 1;
-
-            while (index >= decimal && n[index] == '0')
-            {
-                index--;
-            }
-
-            if (index == decimal)
-            {
-                return n.substr(0, decimal);
-            }
-
-            return n.substr(0, index + 1);
-        };
-
-        write_attribute("left", remove_trailing_zeros(std::to_string(ws.page_margins().left())));
-        write_attribute("right", remove_trailing_zeros(std::to_string(ws.page_margins().right())));
-        write_attribute("top", remove_trailing_zeros(std::to_string(ws.page_margins().top())));
-        write_attribute("bottom", remove_trailing_zeros(std::to_string(ws.page_margins().bottom())));
-        write_attribute("header", remove_trailing_zeros(std::to_string(ws.page_margins().header())));
-        write_attribute("footer", remove_trailing_zeros(std::to_string(ws.page_margins().footer())));
 
         write_end_element(xmlns, "pageMargins");
     }

source/detail/serialization/xlsx_producer.hpp

@@ -28,9 +28,9 @@
 #include <memory>
 #include <vector>
 
+#include <xlnt/utils/numeric.hpp>
 #include <detail/constants.hpp>
 #include <detail/external/include_libstudxml.hpp>
-#include <xlnt/utils/numeric.hpp>
 
 namespace xml {
 class serializer;
@@ -169,19 +169,34 @@ private:
 
     void write_namespace(const std::string &ns, const std::string &prefix);
 
-    template<typename T>
+    // std::string attribute name
+    // not integer or float type
+    template <typename T, typename = std::enable_if_t<!std::is_convertible_v<T, double>>>
     void write_attribute(const std::string &name, T value)
     {
         current_part_serializer_->attribute(name, value);
     }
 
-    template<typename T>
+    void write_attribute(const std::string &name, double value)
+    {
+        current_part_serializer_->attribute(name, converter_.serialise(value));
+    }
+
+    // qname attribute name
+    // not integer or float type
+    template <typename T, typename = std::enable_if_t<!std::is_convertible_v<T, double>>>
     void write_attribute(const xml::qname &name, T value)
     {
         current_part_serializer_->attribute(name, value);
     }
 
-    template<typename T>
+    void write_attribute(const xml::qname &name, double value)
+    {
+        current_part_serializer_->attribute(name, converter_.serialise(value));
+    }
+
+
+    template <typename T>
     void write_characters(T characters, bool preserve_whitespace = false)
     {
         if (preserve_whitespace)