diff --git a/source/module_io/input_conv.cpp b/source/module_io/input_conv.cpp
index 8e3353db56..88a14837c4 100644
--- a/source/module_io/input_conv.cpp
+++ b/source/module_io/input_conv.cpp
@@ -35,25 +35,37 @@ template <typename T> void Input_Conv::parse_expression(const std::string &fn, s
     int count = 0;
     std::string pattern("([0-9]+\\*[0-9.]+|[0-9,.]+)");
     std::vector<std::string> str;
-    std::string::size_type pos1, pos2;
-    std::string c = " ";
-    pos2 = fn.find(c);
-    pos1 = 0;
-    while (std::string::npos != pos2)
-    {
-        str.push_back(fn.substr(pos1, pos2 - pos1));
-        pos1 = pos2 + c.size();
-        pos2 = fn.find(c, pos1);
-    }
-    if (pos1 != fn.length())
-    {
-        str.push_back(fn.substr(pos1));
+    std::stringstream ss(fn);
+    std::string section;
+    while (ss >> section) {
+        int index = 0;
+        if (str.empty()) {
+            while (index < section.size() && std::isspace(section[index])) {
+                index++;
+            }
+        }
+        section.erase(0, index);
+        str.push_back(section);
     }
+    // std::string::size_type pos1, pos2;
+    // std::string c = " ";
+    // pos2 = fn.find(c);
+    // pos1 = 0;
+    // while (std::string::npos != pos2)
+    // {
+    //     str.push_back(fn.substr(pos1, pos2 - pos1));
+    //     pos1 = pos2 + c.size();
+    //     pos2 = fn.find(c, pos1);
+    // }
+    // if (pos1 != fn.length())
+    // {
+    //     str.push_back(fn.substr(pos1));
+    // }
     regex_t reg;
     regcomp(&reg, pattern.c_str(), REG_EXTENDED);
     regmatch_t pmatch[1];
     const size_t nmatch = 1;
-    for (int i = 0; i < str.size(); ++i)
+    for (size_t i = 0; i < str.size(); ++i)
     {
         if (str[i] == "")
         {
@@ -61,7 +73,7 @@ template <typename T> void Input_Conv::parse_expression(const std::string &fn, s
         }
         int status = regexec(&reg, str[i].c_str(), nmatch, pmatch, 0);
         std::string sub_str = "";
-        for (int j = pmatch[0].rm_so; j != pmatch[0].rm_eo; ++j)
+        for (size_t j = pmatch[0].rm_so; j != pmatch[0].rm_eo; ++j)
         {
             sub_str += str[i][j];
         }
@@ -78,8 +90,8 @@ template <typename T> void Input_Conv::parse_expression(const std::string &fn, s
             // std::vector<double> ocp_temp(num, occ);
             // const std::vector<double>::iterator dest = vec.begin() + count;
             // copy(ocp_temp.begin(), ocp_temp.end(), dest);
-            //count += num;
-            for (size_t i = 0; i != num; i++)
+            // count += num;
+            for (size_t k = 0; k != num; k++)
                 vec.emplace_back(occ);
         }
         else