diff --git a/source/module_base/formatter.h b/source/module_base/formatter.h
index 614988f7c3..963964f0ef 100644
--- a/source/module_base/formatter.h
+++ b/source/module_base/formatter.h
@@ -145,6 +145,20 @@ class FmtCore
             [&delim](const std::string& acc, const std::string& s) { return acc + delim + s; });
     }
 
+    static std::string upper(const std::string& in)
+    {
+        std::string dst = in;
+        std::transform(dst.begin(), dst.end(), dst.begin(), ::toupper);
+        return dst;
+    }
+
+    static std::string lower(const std::string& in)
+    {
+        std::string dst = in;
+        std::transform(dst.begin(), dst.end(), dst.begin(), ::tolower);
+        return dst;
+    }
+
 private:
     std::string fmt_;
     template<typename T>
diff --git a/source/module_io/read_input.cpp b/source/module_io/read_input.cpp
index 21235eb461..50bf47f4d1 100644
--- a/source/module_io/read_input.cpp
+++ b/source/module_io/read_input.cpp
@@ -5,6 +5,10 @@
 #include <fstream>
 #include <iostream>
 #include <sstream>
+#include <array>
+#include <vector>
+#include <cassert>
+#include "module_base/formatter.h"
 #include "module_base/global_file.h"
 #include "module_base/global_function.h"
 #include "module_base/tool_quit.h"
@@ -12,72 +16,41 @@
 namespace ModuleIO
 {
 
-void strtolower(char* sa, char* sb)
+std::string longstring(const std::vector<std::string>& words)
 {
-    char c;
-    int len = strlen(sa);
-    for (int i = 0; i < len; i++)
-    {
-        c = sa[i];
-        sb[i] = tolower(c);
-    }
-    sb[len] = '\0';
+    return FmtCore::join(" ", words);
 }
 
-std::string longstring(const std::vector<std::string>& str_values)
+bool assume_as_boolean(const std::string& val)
 {
-    std::string output;
-    output = "";
-    const size_t length = str_values.size();
-    for (int i = 0; i < length; ++i)
-    {
-        output += str_values[i];
-        if (i != length - 1)
-        {
-            output += " ";
-        }
-    }
-    return output;
-}
+    const std::string val_ = FmtCore::lower(val);
 
-bool convert_bool(std::string str)
-{
-    for (auto& i: str)
-    {
-        i = tolower(i);
-    }
-    if (str == "true")
-    {
-        return true;
-    }
-    else if (str == "false")
-    {
-        return false;
-    }
-    else if (str == "1")
-    {
-        return true;
-    }
-    else if (str == "0")
-    {
-        return false;
-    }
-    else if (str == "t")
+    const std::array<std::string, 7> t_ = {"true", "1", "t", "yes", "y", "on", ".true."};
+    const std::array<std::string, 7> f_ = {"false", "0", "f", "no", "n", "off", ".false."};
+    // This will work because std::array<T, N>::size() is a constexpr function
+    // Ouch it is of C++17 standard...
+    // static_assert(t_.size() == f_.size(), "t_ and f_ must have the same lengths");
+#ifdef __DEBUG // C++11 can do this
+    assert(t_.size() == f_.size());
+#endif
+
+    if (std::find(t_.begin(), t_.end(), val_) != t_.end())
     {
         return true;
     }
-    else if (str == "f")
+    else if (std::find(f_.begin(), f_.end(), val_) != f_.end())
     {
         return false;
     }
     else
     {
-        std::string warningstr = "Bad boolean parameter ";
-        warningstr.append(str);
-        warningstr.append(", please check the input parameters in file INPUT");
-        ModuleBase::WARNING_QUIT("Input", warningstr);
+        std::string warnmsg = "Bad boolean parameter ";
+        warnmsg.append(val);
+        warnmsg.append(", please check the input parameters in file INPUT");
+        ModuleBase::WARNING_QUIT("Input", warnmsg);
     }
 }
+
 std::string to_dir(const std::string& str)
 {
     std::string str_dir = str;
@@ -216,8 +189,7 @@ void ReadInput::read_txt_input(Parameter& param, const std::string& filename)
     ifs.clear();
     ifs.seekg(0);
 
-    char word[80];
-    char word1[80];
+    std::string word, word1;
     int ierr = 0;
 
     // ifs >> std::setiosflags(ios::uppercase);
@@ -226,7 +198,7 @@ void ReadInput::read_txt_input(Parameter& param, const std::string& filename)
     {
         ifs >> word;
         ifs.ignore(150, '\n');
-        if (strcmp(word, "INPUT_PARAMETERS") == 0)
+        if (word == "INPUT_PARAMETERS")
         {
             ierr = 1;
             break;
@@ -247,10 +219,8 @@ void ReadInput::read_txt_input(Parameter& param, const std::string& filename)
     while (ifs.good())
     {
         ifs >> word1;
-        if (ifs.eof()) {
-            break;
-}
-        strtolower(word1, word);
+        if (ifs.eof()) { break; }
+        word = FmtCore::lower(word1);
         auto it = std::find_if(input_lists.begin(),
                                input_lists.end(),
                                [&word](const std::pair<std::string, Input_Item>& item) { return item.first == word; });
@@ -311,7 +281,7 @@ void ReadInput::read_txt_input(Parameter& param, const std::string& filename)
         Input_Item* resetvalue_item = &(input_item.second);
         if (resetvalue_item->reset_value != nullptr) {
             resetvalue_item->reset_value(*resetvalue_item, param);
-}
+        }
     }
     this->set_globalv(param);
 
@@ -327,7 +297,7 @@ void ReadInput::read_txt_input(Parameter& param, const std::string& filename)
         Input_Item* checkvalue_item = &(input_item.second);
         if (checkvalue_item->check_value != nullptr) {
             checkvalue_item->check_value(*checkvalue_item, param);
-}
+        }
     }
 }
 
@@ -505,12 +475,6 @@ void ReadInput::add_item(const Input_Item& item)
     }
 }
 
-bool find_str(const std::vector<std::string>& strings, const std::string& strToFind)
-{
-    auto it = std::find(strings.begin(), strings.end(), strToFind);
-    return it != strings.end();
-}
-
 std::string nofound_str(std::vector<std::string> init_chgs, const std::string& str)
 {
     std::string warningstr = "The parameter ";
diff --git a/source/module_io/read_input.h b/source/module_io/read_input.h
index 0bd8745ad7..a39d043fe7 100644
--- a/source/module_io/read_input.h
+++ b/source/module_io/read_input.h
@@ -139,14 +139,10 @@ class ReadInput
     std::vector<std::function<void(Parameter&)>> bcastfuncs;
 };
 
-// convert string to lower case
-void strtolower(char* sa, char* sb);
 // convert string vector to a long string
 std::string longstring(const std::vector<std::string>& str_values);
 // convert string to bool
-bool convert_bool(std::string str);
-// if find a string in a vector of strings
-bool find_str(const std::vector<std::string>& strings, const std::string& strToFind);
+bool assume_as_boolean(const std::string& val);
 // convert to directory format
 std::string to_dir(const std::string& str);
 // return a warning string if the string is not found in the vector
diff --git a/source/module_io/read_input_item_elec_stru.cpp b/source/module_io/read_input_item_elec_stru.cpp
index 6b6b9944e7..cf7ec3cb89 100644
--- a/source/module_io/read_input_item_elec_stru.cpp
+++ b/source/module_io/read_input_item_elec_stru.cpp
@@ -76,7 +76,7 @@ void ReadInput::item_elec_stru()
 
             if (para.input.basis_type == "pw")
             {
-                if (!find_str(pw_solvers, ks_solver))
+                if (std::find(pw_solvers.begin(), pw_solvers.end(), ks_solver) == pw_solvers.end())
                 {
                     const std::string warningstr = "For PW basis: " + nofound_str(pw_solvers, "ks_solver");
                     ModuleBase::WARNING_QUIT("ReadInput", warningstr);
@@ -84,7 +84,7 @@ void ReadInput::item_elec_stru()
             }
             else if (para.input.basis_type == "lcao")
             {
-                if (!find_str(lcao_solvers, ks_solver))
+                if (std::find(lcao_solvers.begin(), lcao_solvers.end(), ks_solver) == lcao_solvers.end())
                 {
                     const std::string warningstr = "For LCAO basis: " + nofound_str(lcao_solvers, "ks_solver");
                     ModuleBase::WARNING_QUIT("ReadInput", warningstr);
@@ -163,7 +163,7 @@ void ReadInput::item_elec_stru()
         };
         item.check_value = [](const Input_Item& item, const Parameter& para) {
             const std::vector<std::string> basis_types = {"pw", "lcao_in_pw", "lcao"};
-            if (!find_str(basis_types, para.input.basis_type))
+            if (std::find(basis_types.begin(), basis_types.end(), para.input.basis_type) == basis_types.end())
             {
                 const std::string warningstr = nofound_str(basis_types, "basis_type");
                 ModuleBase::WARNING_QUIT("ReadInput", warningstr);
diff --git a/source/module_io/read_input_item_output.cpp b/source/module_io/read_input_item_output.cpp
index d0001e805d..03742d24d0 100644
--- a/source/module_io/read_input_item_output.cpp
+++ b/source/module_io/read_input_item_output.cpp
@@ -11,7 +11,7 @@ void ReadInput::item_output()
         item.annotation = "output the structure files after each ion step";
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             const std::vector<std::string> offlist = {"nscf", "get_S", "get_pchg", "get_wf"};
-            if (find_str(offlist, para.input.calculation))
+            if (std::find(offlist.begin(), offlist.end(), para.input.calculation) != offlist.end())
             {
                 para.input.out_stru = false;
             }
@@ -96,21 +96,13 @@ void ReadInput::item_output()
         Input_Item item("out_band");
         item.annotation = "output energy and band structure (with precision 8)";
         item.read_value = [](const Input_Item& item, Parameter& para) {
-            size_t count = item.get_size();
-            if (count == 1)
-            {
-                para.input.out_band[0] = std::stoi(item.str_values[0]);
-                para.input.out_band[1] = 8;
-            }
-            else if (count == 2)
-            {
-                para.input.out_band[0] = std::stoi(item.str_values[0]);
-                para.input.out_band[1] = std::stoi(item.str_values[1]);
-            }
-            else
+            const size_t count = item.get_size();
+            if (count != 1 && count != 2)
             {
                 ModuleBase::WARNING_QUIT("ReadInput", "out_band should have 1 or 2 values");
             }
+            para.input.out_band[0] = assume_as_boolean(item.str_values[0]);
+            para.input.out_band[1] = (count == 2) ? std::stoi(item.str_values[1]) : 8;
         };
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             if (para.input.calculation == "get_wf" || para.input.calculation == "get_pchg")
@@ -239,21 +231,13 @@ void ReadInput::item_output()
         Input_Item item("out_mat_hs");
         item.annotation = "output H and S matrix (with precision 8)";
         item.read_value = [](const Input_Item& item, Parameter& para) {
-            size_t count = item.get_size();
-            if (count == 1)
-            {
-                para.input.out_mat_hs[0] = std::stoi(item.str_values[0]);
-                para.input.out_mat_hs[1] = 8;
-            }
-            else if (count == 2)
-            {
-                para.input.out_mat_hs[0] = std::stoi(item.str_values[0]);
-                para.input.out_mat_hs[1] = std::stoi(item.str_values[1]);
-            }
-            else
+            const size_t count = item.get_size();
+            if (count != 1 && count != 2)
             {
                 ModuleBase::WARNING_QUIT("ReadInput", "out_mat_hs should have 1 or 2 values");
             }
+            para.input.out_mat_hs[0] = assume_as_boolean(item.str_values[0]);
+            para.input.out_mat_hs[1] = (count == 2) ? std::stoi(item.str_values[1]) : 8;
         };
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             if (para.input.qo_switch)
@@ -268,21 +252,13 @@ void ReadInput::item_output()
         Input_Item item("out_mat_tk");
         item.annotation = "output T(k)";
         item.read_value = [](const Input_Item& item, Parameter& para) {
-            size_t count = item.get_size();
-            if (count == 1)
-            {
-                para.input.out_mat_tk[0] = std::stoi(item.str_values[0]);
-                para.input.out_mat_tk[1] = 8;
-            }
-            else if (count == 2)
-            {
-                para.input.out_mat_tk[0] = std::stoi(item.str_values[0]);
-                para.input.out_mat_tk[1] = std::stoi(item.str_values[1]);
-            }
-            else
+            const size_t count = item.get_size();
+            if (count != 1 && count != 2)
             {
                 ModuleBase::WARNING_QUIT("ReadInput", "out_mat_tk should have 1 or 2 values");
             }
+            para.input.out_mat_tk[0] = assume_as_boolean(item.str_values[0]);
+            para.input.out_mat_tk[1] = (count == 2) ? std::stoi(item.str_values[1]) : 8;
         };
         sync_intvec(input.out_mat_tk, 2, 0);
         this->add_item(item);
diff --git a/source/module_io/read_input_item_relax.cpp b/source/module_io/read_input_item_relax.cpp
index c9545576c2..f222b25ef9 100644
--- a/source/module_io/read_input_item_relax.cpp
+++ b/source/module_io/read_input_item_relax.cpp
@@ -13,7 +13,7 @@ void ReadInput::item_relax()
         read_sync_string(input.relax_method);
         item.check_value = [](const Input_Item& item, const Parameter& para) {
             const std::vector<std::string> relax_methods = {"cg", "bfgs", "sd", "cg_bfgs"};
-            if (!find_str(relax_methods, para.input.relax_method))
+            if (std::find(relax_methods.begin(), relax_methods.end(), para.input.relax_method) == relax_methods.end())
             {
                 const std::string warningstr = nofound_str(relax_methods, "relax_method");
                 ModuleBase::WARNING_QUIT("ReadInput", warningstr);
@@ -52,7 +52,7 @@ void ReadInput::item_relax()
             const std::string& calculation = para.input.calculation;
             const std::vector<std::string> singlelist
                 = {"scf", "nscf", "get_S", "get_pchg", "get_wf", "test_memory", "test_neighbour", "gen_bessel"};
-            if (find_str(singlelist, calculation))
+            if (std::find(singlelist.begin(), singlelist.end(), calculation) != singlelist.end())
             {
                 para.input.relax_nmax = 1;
             }
diff --git a/source/module_io/read_input_item_system.cpp b/source/module_io/read_input_item_system.cpp
index 1ceae0b79c..7398dc2e6a 100644
--- a/source/module_io/read_input_item_system.cpp
+++ b/source/module_io/read_input_item_system.cpp
@@ -80,7 +80,7 @@ void ReadInput::item_system()
                                                 "get_wf",
                                                 "get_pchg",
                                                 "gen_bessel"};
-            if (!find_str(callist, calculation))
+            if (std::find(callist.begin(), callist.end(), calculation) == callist.end())
             {
                 const std::string warningstr = nofound_str(callist, "calculation");
                 ModuleBase::WARNING_QUIT("ReadInput", warningstr);
@@ -111,7 +111,7 @@ void ReadInput::item_system()
         read_sync_string(input.esolver_type);
         item.check_value = [](const Input_Item& item, const Parameter& para) {
             const std::vector<std::string> esolver_types = { "ksdft", "sdft", "ofdft", "tddft", "lj", "dp", "lr", "ks-lr" };
-            if (!find_str(esolver_types, para.input.esolver_type))
+            if (std::find(esolver_types.begin(), esolver_types.end(), para.input.esolver_type) == esolver_types.end())
             {
                 const std::string warningstr = nofound_str(esolver_types, "esolver_type");
                 ModuleBase::WARNING_QUIT("ReadInput", warningstr);
@@ -208,7 +208,7 @@ void ReadInput::item_system()
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             std::vector<std::string> use_force = {"cell-relax", "relax", "md"};
             std::vector<std::string> not_use_force = {"get_wf", "get_pchg", "nscf", "get_S"};
-            if (find_str(use_force, para.input.calculation))
+            if (std::find(use_force.begin(), use_force.end(), para.input.calculation) != use_force.end())
             {
                 if (!para.input.cal_force)
                 {
@@ -216,7 +216,7 @@ void ReadInput::item_system()
                 }
                 para.input.cal_force = true;
             }
-            else if (find_str(not_use_force, para.input.calculation))
+            else if (std::find(not_use_force.begin(), not_use_force.end(), para.input.calculation) != not_use_force.end())
             {
                 if (para.input.cal_force)
                 {
@@ -538,7 +538,7 @@ void ReadInput::item_system()
         };
         item.check_value = [](const Input_Item& item, const Parameter& para) {
             const std::vector<std::string> init_chgs = {"atomic", "file", "wfc", "auto"};
-            if (!find_str(init_chgs, para.input.init_chg))
+            if (std::find(init_chgs.begin(), init_chgs.end(), para.input.init_chg) == init_chgs.end())
             {
                 const std::string warningstr = nofound_str(init_chgs, "init_chg");
                 ModuleBase::WARNING_QUIT("ReadInput", warningstr);
diff --git a/source/module_io/read_input_tool.h b/source/module_io/read_input_tool.h
index 9df14d0e67..665d045ce8 100644
--- a/source/module_io/read_input_tool.h
+++ b/source/module_io/read_input_tool.h
@@ -8,7 +8,7 @@
 #define strvalue item.str_values[0]
 #define intvalue std::stoi(item.str_values[0])
 #define doublevalue std::stod(item.str_values[0])
-#define boolvalue convert_bool(item.str_values[0])
+#define boolvalue assume_as_boolean(item.str_values[0])
 
 #ifdef __MPI
 #define add_double_bcast(PARAMETER)                                                                                    \