diff --git a/src/addhead.cpp b/src/addhead.cpp
index da7bccb..23e62b8 100644
--- a/src/addhead.cpp
+++ b/src/addhead.cpp
@@ -205,7 +205,7 @@ bool AdditionalHeader::AddHeader(headers_t& meta, const char* path) const
         }else{
             // directly comparing
             if(paddhead->basestring.length() < pathlength){
-                if(0 == paddhead->basestring.length() || 0 == strcmp(&path[pathlength - paddhead->basestring.length()], paddhead->basestring.c_str())){
+                if(paddhead->basestring.empty() || 0 == strcmp(&path[pathlength - paddhead->basestring.length()], paddhead->basestring.c_str())){
                     // match -> adding header
                     meta[paddhead->headkey] = paddhead->headvalue;
                 }
diff --git a/src/curl.cpp b/src/curl.cpp
index f41704e..7078bfd 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -953,7 +953,7 @@ bool S3fsCurl::LoadEnvSseKmsid()
 bool S3fsCurl::GetSseKey(std::string& md5, std::string& ssekey)
 {
     for(sseckeylist_t::const_iterator iter = S3fsCurl::sseckeys.begin(); iter != S3fsCurl::sseckeys.end(); ++iter){
-        if(0 == md5.length() || md5 == (*iter).begin()->first){
+        if(md5.empty() || md5 == (*iter).begin()->first){
             md5    = iter->begin()->first;
             ssekey = iter->begin()->second;
             return true;
@@ -2658,7 +2658,7 @@ void S3fsCurl::insertV4Headers()
             break;
     }
 
-    if(b_infile != NULL && 0 == payload_hash.length()){
+    if(b_infile != NULL && payload_hash.empty()){
         S3FS_PRN_ERR("Failed to make SHA256.");
         // TODO: propagate error
     }
diff --git a/src/curl.h b/src/curl.h
index 9d6037e..0b841a7 100644
--- a/src/curl.h
+++ b/src/curl.h
@@ -329,11 +329,11 @@ class S3fsCurl
         static bool SetAccessKeyWithSessionToken(const char* AccessKeyId, const char* SecretAccessKey, const char * SessionToken);
         static bool IsSetAccessKeyID()
         {
-            return (0 < S3fsCurl::AWSAccessKeyId.size());
+            return !S3fsCurl::AWSAccessKeyId.empty();
         }
         static bool IsSetAccessKeys()
         {
-            return (0 < S3fsCurl::IAM_role.size() || ((0 < S3fsCurl::AWSAccessKeyId.size() || S3fsCurl::is_ibm_iam_auth) && 0 < S3fsCurl::AWSSecretAccessKey.size()));
+            return !S3fsCurl::IAM_role.empty() || ((!S3fsCurl::AWSAccessKeyId.empty() || S3fsCurl::is_ibm_iam_auth) && !S3fsCurl::AWSSecretAccessKey.empty());
         }
         static long SetSslVerifyHostname(long value);
         static long GetSslVerifyHostname() { return S3fsCurl::ssl_verify_hostname; }
diff --git a/src/curl_util.cpp b/src/curl_util.cpp
index 1a9655e..f5b4345 100644
--- a/src/curl_util.cpp
+++ b/src/curl_util.cpp
@@ -145,7 +145,7 @@ std::string get_sorted_header_keys(const struct curl_slist* list)
             }
             strkey.erase(pos);
         }
-        if(0 < sorted_headers.length()){
+        if(!sorted_headers.empty()){
             sorted_headers += ";";
         }
         sorted_headers += lower(strkey);
@@ -317,7 +317,7 @@ bool make_md5_from_binary(const char* pstr, size_t length, std::string& md5)
     }
     // base64 md5
     md5 = s3fs_get_content_md5(fd);
-    if(0 == md5.length()){
+    if(md5.empty()){
         S3FS_PRN_ERR("Failed to make MD5.");
         fclose(fp);
         return false;
diff --git a/src/s3fs.cpp b/src/s3fs.cpp
index 63a7711..8faa5a9 100644
--- a/src/s3fs.cpp
+++ b/src/s3fs.cpp
@@ -277,7 +277,7 @@ static int chk_dir_object_type(const char* path, std::string& newpath, std::stri
             nowpath  = "";
         }else{
             nowpath = newpath;
-            if(0 < nowpath.length() && '/' == *nowpath.rbegin()){
+            if(!nowpath.empty() && '/' == *nowpath.rbegin()){
                 // "dir/" type
                 (*pType) = DIRTYPE_NEW;
             }else{
@@ -2694,7 +2694,7 @@ static int list_bucket(const char* path, S3ObjList& head, const char* delimiter,
 
     query_prefix += "&prefix=";
     s3_realpath = get_realpath(path);
-    if(0 == s3_realpath.length() || '/' != *s3_realpath.rbegin()){
+    if(s3_realpath.empty() || '/' != *s3_realpath.rbegin()){
         // last word must be "/"
         query_prefix += urlEncode(s3_realpath.substr(1) + "/");
     }else{
@@ -2764,7 +2764,7 @@ static int list_bucket(const char* path, S3ObjList& head, const char* delimiter,
                     truncated = false;
                 }else{
                     next_marker = s3_realpath.substr(1);
-                    if(0 == s3_realpath.length() || '/' != *s3_realpath.rbegin()){
+                    if(s3_realpath.empty() || '/' != *s3_realpath.rbegin()){
                         next_marker += "/";
                     }
                     next_marker += lastname;
@@ -2858,7 +2858,7 @@ static size_t parse_xattrs(const std::string& strxattrs, xattrs_t& xattrs)
     }
 
     // parse each key:val
-    for(size_t pair_nextpos = restxattrs.find_first_of(','); 0 < restxattrs.length(); restxattrs = (pair_nextpos != std::string::npos ? restxattrs.substr(pair_nextpos + 1) : std::string("")), pair_nextpos = restxattrs.find_first_of(',')){
+    for(size_t pair_nextpos = restxattrs.find_first_of(','); !restxattrs.empty(); restxattrs = (pair_nextpos != std::string::npos ? restxattrs.substr(pair_nextpos + 1) : std::string("")), pair_nextpos = restxattrs.find_first_of(',')){
         std::string pair = pair_nextpos != std::string::npos ? restxattrs.substr(0, pair_nextpos) : restxattrs;
         std::string key;
         PXATTRVAL pval = NULL;
@@ -3190,7 +3190,7 @@ static int s3fs_listxattr(const char* path, char* list, size_t size)
     // calculate total name length
     size_t total = 0;
     for(xattrs_t::const_iterator xiter = xattrs.begin(); xiter != xattrs.end(); ++xiter){
-        if(0 < xiter->first.length()){
+        if(!xiter->first.empty()){
             total += xiter->first.length() + 1;
         }
     }
@@ -3213,7 +3213,7 @@ static int s3fs_listxattr(const char* path, char* list, size_t size)
     // copy to list
     char* setpos = list;
     for(xattrs_t::const_iterator xiter = xattrs.begin(); xiter != xattrs.end(); ++xiter){
-        if(0 < xiter->first.length()){
+        if(!xiter->first.empty()){
             strcpy(setpos, xiter->first.c_str());
             setpos = &setpos[strlen(setpos) + 1];
         }
diff --git a/src/s3fs_xml.cpp b/src/s3fs_xml.cpp
index 84b6881..3daa029 100644
--- a/src/s3fs_xml.cpp
+++ b/src/s3fs_xml.cpp
@@ -175,7 +175,7 @@ static char* get_object_name(xmlDocPtr doc, xmlNodePtr node, const char* path)
                 if(strlen(dirpath) > strlen(basepath)){
                     withdirname = &dirpath[strlen(basepath)];
                 }
-                if(0 < withdirname.length() && '/' != *withdirname.rbegin()){
+                if(!withdirname.empty() && '/' != *withdirname.rbegin()){
                     withdirname += "/";
                 }
                 withdirname += mybname;
@@ -378,7 +378,7 @@ int append_objects_from_xml_ex(const char* path, xmlDocPtr doc, xmlXPathContextP
                     xmlXPathFreeObject(ETag);
                 }
             }
-            if(!head.insert(name, (0 < stretag.length() ? stretag.c_str() : NULL), is_dir)){
+            if(!head.insert(name, (!stretag.empty() ? stretag.c_str() : NULL), is_dir)){
                 S3FS_PRN_ERR("insert_object returns with error.");
                 xmlXPathFreeObject(key);
                 xmlXPathFreeObject(contents_xp);
diff --git a/src/s3objlist.cpp b/src/s3objlist.cpp
index e31193b..cde89d3 100644
--- a/src/s3objlist.cpp
+++ b/src/s3objlist.cpp
@@ -165,7 +165,7 @@ std::string S3ObjList::GetNormalizedName(const char* name) const
     if(NULL == (ps3obj = GetS3Obj(name))){
         return std::string("");
     }
-    if(0 == (ps3obj->normalname).length()){
+    if(ps3obj->normalname.empty()){
         return std::string(name);
     }
     return ps3obj->normalname;
@@ -219,7 +219,7 @@ bool S3ObjList::GetNameList(s3obj_list_t& list, bool OnlyNormalized, bool CutSla
     s3obj_t::const_iterator iter;
 
     for(iter = objects.begin(); objects.end() != iter; ++iter){
-        if(OnlyNormalized && 0 != (*iter).second.normalname.length()){
+        if(OnlyNormalized && !iter->second.normalname.empty()){
             continue;
         }
         std::string name = (*iter).first;
@@ -250,7 +250,7 @@ bool S3ObjList::MakeHierarchizedList(s3obj_list_t& list, bool haveSlash)
         // check hierarchized directory
         for(std::string::size_type pos = strtmp.find_last_of('/'); std::string::npos != pos; pos = strtmp.find_last_of('/')){
             strtmp.erase(pos);
-            if(0 == strtmp.length() || "/" == strtmp){
+            if(strtmp.empty() || "/" == strtmp){
                 break;
             }
             if(h_map.end() == h_map.find(strtmp)){