From f3ef0779b5c7dafdc05919b2cbf850c649c1e702 Mon Sep 17 00:00:00 2001
From: Philipp Moritz <pcmoritz@gmail.com>
Date: Tue, 5 Feb 2019 17:09:29 -0800
Subject: [PATCH 1/2] use stringstreams instead of std::to_string and std::stoi

---
 cpp/src/arrow/python/deserialize.cc | 7 +++++--
 cpp/src/arrow/python/serialize.cc   | 5 +++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/cpp/src/arrow/python/deserialize.cc b/cpp/src/arrow/python/deserialize.cc
index f13070a5883..13fc73c70a8 100644
--- a/cpp/src/arrow/python/deserialize.cc
+++ b/cpp/src/arrow/python/deserialize.cc
@@ -22,6 +22,7 @@
 #include <cstdint>
 #include <memory>
 #include <string>
+#include <sstream>
 #include <utility>
 #include <vector>
 
@@ -195,8 +196,10 @@ std::vector<int8_t> GetPythonTypes(const UnionArray& data) {
   std::vector<int8_t> result;
   auto type = data.type();
   for (int i = 0; i < type->num_children(); ++i) {
-    // stoi is locale dependent, but should be ok for small integers
-    result.push_back(static_cast<int8_t>(std::stoi(type->child(i)->name())));
+    std::istringstream convert(type->child(i)->name());
+    int8_t tag;
+    convert >> tag;
+    result.push_back(tag);
   }
   return result;
 }
diff --git a/cpp/src/arrow/python/serialize.cc b/cpp/src/arrow/python/serialize.cc
index 3ccdfc8eee5..17f3dba4cff 100644
--- a/cpp/src/arrow/python/serialize.cc
+++ b/cpp/src/arrow/python/serialize.cc
@@ -90,8 +90,9 @@ class SequenceBuilder {
                          MakeBuilderFn make_builder) {
     if (!*child_builder) {
       child_builder->reset(make_builder());
-      // std::to_string is locale dependent, but should be ok for small integers
-      type_map_[tag] = builder_->AppendChild(*child_builder, std::to_string(tag));
+      std::ostringstream convert;
+      convert << tag;
+      type_map_[tag] = builder_->AppendChild(*child_builder, convert.str());
     }
     return Update(child_builder->get(), type_map_[tag]);
   }

From 7c8b81da169d10eece377944618217d198adc05e Mon Sep 17 00:00:00 2001
From: Philipp Moritz <pcmoritz@gmail.com>
Date: Tue, 5 Feb 2019 20:44:14 -0800
Subject: [PATCH 2/2] update

---
 cpp/src/arrow/python/deserialize.cc | 6 +++---
 cpp/src/arrow/python/serialize.cc   | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/cpp/src/arrow/python/deserialize.cc b/cpp/src/arrow/python/deserialize.cc
index 13fc73c70a8..979399646ad 100644
--- a/cpp/src/arrow/python/deserialize.cc
+++ b/cpp/src/arrow/python/deserialize.cc
@@ -21,8 +21,8 @@
 
 #include <cstdint>
 #include <memory>
-#include <string>
 #include <sstream>
+#include <string>
 #include <utility>
 #include <vector>
 
@@ -197,9 +197,9 @@ std::vector<int8_t> GetPythonTypes(const UnionArray& data) {
   auto type = data.type();
   for (int i = 0; i < type->num_children(); ++i) {
     std::istringstream convert(type->child(i)->name());
-    int8_t tag;
+    int tag;
     convert >> tag;
-    result.push_back(tag);
+    result.push_back(static_cast<int8_t>(tag));
   }
   return result;
 }
diff --git a/cpp/src/arrow/python/serialize.cc b/cpp/src/arrow/python/serialize.cc
index 17f3dba4cff..4d5b02984cf 100644
--- a/cpp/src/arrow/python/serialize.cc
+++ b/cpp/src/arrow/python/serialize.cc
@@ -91,7 +91,7 @@ class SequenceBuilder {
     if (!*child_builder) {
       child_builder->reset(make_builder());
       std::ostringstream convert;
-      convert << tag;
+      convert << static_cast<int>(tag);
       type_map_[tag] = builder_->AppendChild(*child_builder, convert.str());
     }
     return Update(child_builder->get(), type_map_[tag]);