diff --git a/Autoarr/StringBuilder.h b/Autoarr/StringBuilder.h
deleted file mode 100644
index 0b52429..0000000
--- a/Autoarr/StringBuilder.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#pragma once
-
-#if __cplusplus
-extern "C" {
-#endif
-
-#include "Autoarr.h"
-
-	typedef Autoarr(int8) StringBuilder;
-
-	StringBuilder StringBuilder_create(uint16 max_blocks_count, uint16 max_block_length);
-	void StringBuilder_append_char(StringBuilder* b, char c);
-	void StringBuilder_append_cptr(StringBuilder* b, char* s);
-	void StringBuilder_append_string(StringBuilder* b, string s);
-	void StringBuilder_append_int64(StringBuilder* b, int64 a);
-	void StringBuilder_append_uint64(StringBuilder* b, uint64 a);
-	void StringBuilder_append_double(StringBuilder* b, double a);
-	char* StringBuilder_build(StringBuilder* b);
-
-#if __cplusplus
-}
-#endif
\ No newline at end of file
diff --git a/DtsodParser/DtsodV24_deserialize.c b/DtsodParser/DtsodV24_deserialize.c
index 7e3a354..686f8c5 100644
--- a/DtsodParser/DtsodV24_deserialize.c
+++ b/DtsodParser/DtsodV24_deserialize.c
@@ -1,24 +1,40 @@
 #include "DtsodV24.h"
-#include "../Autoarr/StringBuilder.h"
+#include "../StringFragment/StringBuilder.h"
 
 #define ARR_BC 8
 #define ARR_BL 16
 #define STRB_BC 64
 #define STRB_BL 1024
 
-Maybe ERROR_WRONGCHAR(char c, char* text){
-    char errBuf[]="unexpected <c> at:\n  \""
-        "00000000000000000000000000000000\"";
-    errBuf[12]=c;
-    for(uint8 i=0; i<32; i++)
-        // writes 16 chars before and 15 after the wrongchar
-        errBuf[i+22]=*(text - 16 + i);
-    safethrow(cptr_copy(errBuf));
+Maybe ERROR_WRONGCHAR(const char c, char* text, char* text_first, const char* srcfile, int line, const char* funcname){
+    char errBuf[33];
+    errBuf[32]='\0';
+    char* errText=text-16;
+    if(errText<text_first) errText=text_first;
+    for(uint8 i=0; i<32; i++){
+        //writes 16 chars before and 15 after the wrongchar
+        char _c=errText[i];
+        errBuf[i]=_c;
+        if(!_c) break;
+    }
+    char* errmsg=malloc(256);
+    IFWIN(
+        sprintf_s(errmsg,256, "unexpected <%c> at:\n"
+                        "  \"%s\"\n"
+                        "\\___[%s:%d] %s()", 
+                        c,errBuf, srcfile,line,funcname),
+        sprintf(errmsg, "unexpected <%c> at:\n"
+                        "  \"%s\"\n"
+                        " \\___[%s:%d] %s()", 
+                        c,errBuf, srcfile,line,funcname)
+    );
+    safethrow(cptr_copy(errmsg));
 }
-#define safethrow_wrongchar(C) return ERROR_WRONGCHAR(C, text)
+#define safethrow_wrongchar(C) return ERROR_WRONGCHAR(C, text, shared->sh_text_first, __FILE__,__LINE__,__func__)
 
 
 typedef struct DeserializeSharedData{
+    const char* sh_text_first; 
     char* sh_text;
     bool sh_partOfDollarList;
     bool sh_readingList;
@@ -39,7 +55,7 @@ Maybe __SkipComment(DeserializeSharedData* shared) {
 
 Maybe __ReadName(DeserializeSharedData* shared){
     char c;
-    string nameStr={text,0};
+    StringFragment nameStr={text,0};
     text--;
     while ((c=*++text)) switch (c){
         case ' ':  case '\t':
@@ -65,7 +81,7 @@ Maybe __ReadName(DeserializeSharedData* shared){
             if((*++text)!=';')
                 safethrow_wrongchar(c);
         case ':':
-            return SUCCESS(UniPtr(CharPtr,string_cpToCptr(nameStr)));
+            return SUCCESS(UniPtr(CharPtr,StringFragment_extract(nameStr).ptr));
         case '$':
             if(nameStr.length!=0)
                 safethrow_wrongchar(c);
@@ -100,9 +116,9 @@ Maybe __ReadString(DeserializeSharedData* shared){
                 StringBuilder_append_char(b,c);
             }
             else {
-                char* str=StringBuilder_build(b);
+                StringFragment str=StringBuilder_build(b);
                 Autoarr_clear(b);
-                return SUCCESS(UniPtr(CharPtr,str));
+                return SUCCESS(UniPtr(CharPtr,str.ptr));
             }
         } 
         else {
@@ -127,68 +143,62 @@ Maybe __ReadList(DeserializeSharedData* shared){
 };
 #define ReadList() __ReadList(shared)
 
-Maybe __ParseValue(DeserializeSharedData* shared, string str){
-    //printf("\e[94m<\e[96m%s\e[94m>\n",string_cpToCptr(str));
-    const string nullStr={"null",4};
-    const string trueStr={"true",4};
-    const string falseStr={"false",5};
-    switch(*str.ptr){
-        case 'n':
-            if(string_compare(str,nullStr))
-                return SUCCESS(UniNull);
-            else safethrow_wrongchar(*str.ptr);
-            break;
-        case 't':
-            if(string_compare(str,trueStr))
+Maybe __ParseValue(DeserializeSharedData* shared, StringFragment str){
+    //printf("\e[94m<\e[96m%s\e[94m>\n",StringFragment_extract(str));
+    const StringFragment trueStr= {"true" ,0,4};
+    const StringFragment falseStr={"false",0,5};
+    switch(str.ptr[str.length-1]){
+        //Bool
+        case 'e': {
+            if(StringFragment_compare(str,trueStr))
                 return SUCCESS(UniTrue);
-            else safethrow_wrongchar(*str.ptr);
-            break;
-        case 'f':
-            if(string_compare(str,falseStr))
+            else if(StringFragment_compare(str,falseStr))
                 return SUCCESS(UniFalse);
             else safethrow_wrongchar(*str.ptr);
-            break;
-        default: 
-            switch(str.ptr[str.length-1]){
-                case 'f': {
-                        char* _c=string_cpToCptr(str);
-                        Unitype rez=Uni(Float64,strtod(_c,NULL));
-                        free(_c);
-                        return SUCCESS(rez);
-                    }
-                case 'u': {
-                        uint64 lu=0;
-                        char* _c=string_cpToCptr(str);
-                        sscanf(_c,"%lu",&lu);
-                        free(_c);
-                        return SUCCESS(Uni(UInt64,lu));
-                    }
-                case '0': case '1': case '2': case '3': case '4':
-                case '5': case '6': case '7': case '8': case '9': {
-                        int64 li=0;
-                        char* _c=string_cpToCptr(str);
-                        if(sscanf(_c,"%li",&li)!=1){
-                            char err[64];
-                            IFWIN(
-                                sprintf_s(err,64,"can't parse to int: <%s>",_c),
-                                sprintf(err,"can't parse to int: <%s>",_c)
-                            );
-                            safethrow(err);
-                        }
-                        free(_c);
-                        return SUCCESS(Uni(Int64,li));
-                    }
-                default:
-                    safethrow_wrongchar(str.ptr[str.length-1]);
+        }
+        //Float64
+        case 'f': {
+            char* _c=StringFragment_extract(str).ptr;
+            Unitype rez=Uni(Float64,strtod(_c,NULL));
+            free(_c);
+            return SUCCESS(rez);
+        }
+        //UInt64
+        case 'u': {
+            uint64 lu=0;
+            char* _c=StringFragment_extract(str).ptr;
+            sscanf(_c,"%lu",&lu);
+            free(_c);
+            return SUCCESS(Uni(UInt64,lu));
+        }
+        //Int64
+        case '0': case '1': case '2': case '3': case '4':
+        case '5': case '6': case '7': case '8': case '9': {
+            int64 li=0;
+            char* _c=StringFragment_extract(str).ptr;
+            if(sscanf(_c,"%li",&li)!=1){
+                char err[64];
+                IFWIN(
+                    sprintf_s(err,64,"can't parse to int: <%s>",_c),
+                    sprintf(err,"can't parse to int: <%s>",_c)
+                );
+                safethrow(err);
             }
+            free(_c);
+            return SUCCESS(Uni(Int64,li));
+        }
+        //unknown type
+        default:
+            safethrow_wrongchar(str.ptr[str.length-1]);
     }
+    
     safethrow(ERR_ENDOFSTR);
 };
 #define ParseValue(str) __ParseValue(shared, str)
 
 Maybe __ReadValue(DeserializeSharedData* shared){
     char c;
-    string valueStr={text+1,0};
+    StringFragment valueStr={text+1,0};
     Unitype value;
     while ((c=*++text)) switch (c){
         case ' ':  case '\t':
@@ -244,6 +254,7 @@ Maybe __ReadValue(DeserializeSharedData* shared){
 
 Maybe __deserialize(char** _text, bool _calledRecursively) {
     DeserializeSharedData _shared={
+        .sh_text_first=*_text,
         .sh_text=*_text,
         .sh_partOfDollarList=false,
         .sh_readingList=false,
diff --git a/DtsodParser/DtsodV24_serialize.c b/DtsodParser/DtsodV24_serialize.c
index 5b7c455..bf87775 100644
--- a/DtsodParser/DtsodV24_serialize.c
+++ b/DtsodParser/DtsodV24_serialize.c
@@ -1,5 +1,5 @@
 #include "DtsodV24.h"
-#include "../Autoarr/StringBuilder.h"
+#include "../StringFragment/StringBuilder.h"
 
 //65536 max length!
 #define STRB_BC 64
@@ -51,8 +51,7 @@ void __AppendValue(SerializeSharedData* shared, Unitype u){
                 StringBuilder_append_cptr(b, u.Bool ? "true" : "false");
                 break;
             case Null:
-                if(!u.VoidPtr) StringBuilder_append_cptr(b, "null");
-                else throw("Null-type pointer is not 0");
+                throw("Null isn't supported in DtsodV24");
                 break;
             case AutoarrUnitypePtr:
                 addc('[');
@@ -97,7 +96,7 @@ void __serialize(StringBuilder* _b, uint8 _tabs, Hashtable* dtsod){
 char* DtsodV24_serialize(Hashtable* dtsod){
     StringBuilder sb=StringBuilder_create(STRB_BC,STRB_BL);
     __serialize(&sb,0,dtsod);
-    char* str=StringBuilder_build(&sb);
+    StringFragment str=StringBuilder_build(&sb);
     Autoarr_clear((&sb));
-    return str;
+    return str.ptr;
 }
diff --git a/Autoarr/StringBuilder.c b/StringFragment/StringBuilder.c
similarity index 70%
rename from Autoarr/StringBuilder.c
rename to StringFragment/StringBuilder.c
index 6a12265..4066c5a 100644
--- a/Autoarr/StringBuilder.c
+++ b/StringFragment/StringBuilder.c
@@ -14,11 +14,10 @@ void StringBuilder_append_cptr(StringBuilder* b, char* s){
         Autoarr_add(b,c);
 }
 
-void StringBuilder_append_string(StringBuilder* b, string s){
-    while(s.length>0){
+void StringBuilder_append_string(StringBuilder* b, StringFragment s){
+    s.ptr+=s.offset;
+    while(s.length-->0)
         Autoarr_add(b,*s.ptr++);
-        s.length--;
-    }
 }
 
 void StringBuilder_append_int64(StringBuilder* b, int64 a){
@@ -36,7 +35,7 @@ void StringBuilder_append_int64(StringBuilder* b, int64 a){
         buf[i++]='0'+a%10;
         a/=10;
     }
-    string rev=string_reverse((string){buf,i});
+    StringFragment rev=StringFragment_reverse((StringFragment){buf,0,i});
     StringBuilder_append_string(b,rev);
     free(rev.ptr);
 }
@@ -52,8 +51,7 @@ void StringBuilder_append_uint64(StringBuilder* b, uint64 a){
         buf[i++]='0'+a%10;
         a/=10;
     }
-    string rev=string_reverse((string){buf,i});
-    printf("\e[95mrev:%s\n",string_cpToCptr(rev));
+    StringFragment rev=StringFragment_reverse((StringFragment){buf,0,i});
     StringBuilder_append_string(b,rev);
     free(rev.ptr);
 }
@@ -67,11 +65,14 @@ void StringBuilder_append_double(StringBuilder* b, double a){
     StringBuilder_append_cptr(b,buf);
 }
 
-char* StringBuilder_build(StringBuilder* b){
-    uint32 len=Autoarr_length(b);
-    char* str=malloc(len+1);
-    str[len]=0;
-    for(uint32 i=0;i<len;i++)
-        str[i]=Autoarr_get(b,i);
+StringFragment StringBuilder_build(StringBuilder* b){
+    StringFragment str={
+        .offset=0,
+        .length=Autoarr_length(b)
+    };
+    str.ptr=malloc(str.length+1);
+    for(uint32 i=0; i<str.length; i++)
+        str.ptr[i]=Autoarr_get(b,i);
+    str.ptr[str.length]='\0';
     return str;
 }
diff --git a/StringFragment/StringBuilder.h b/StringFragment/StringBuilder.h
new file mode 100644
index 0000000..8dff2db
--- /dev/null
+++ b/StringFragment/StringBuilder.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#if __cplusplus
+extern "C" {
+#endif
+
+#include "../Autoarr/Autoarr.h"
+#include "StringFragment.h"
+
+typedef Autoarr(int8) StringBuilder;
+
+StringBuilder StringBuilder_create(uint16 max_blocks_count, uint16 max_block_length);
+void StringBuilder_append_char(StringBuilder* b, char c);
+void StringBuilder_append_cptr(StringBuilder* b, char* s);
+void StringBuilder_append_string(StringBuilder* b, StringFragment s);
+void StringBuilder_append_int64(StringBuilder* b, int64 a);
+void StringBuilder_append_uint64(StringBuilder* b, uint64 a);
+void StringBuilder_append_double(StringBuilder* b, double a);
+//returns StringFragment with '\0' at the end
+StringFragment StringBuilder_build(StringBuilder* b);
+
+#if __cplusplus
+}
+#endif
\ No newline at end of file
diff --git a/StringFragment/StringFragment.c b/StringFragment/StringFragment.c
new file mode 100644
index 0000000..4cb6f2b
--- /dev/null
+++ b/StringFragment/StringFragment.c
@@ -0,0 +1,42 @@
+#include "StringFragment.h"
+
+//copies <length> characters from <ptr+offset> to new StringFragment (adding '\0' at the end)
+StringFragment StringFragment_extract(StringFragment str){
+    if(str.length==0) return stringNull;
+    StringFragment extr={
+        .offset=0,
+        .length=str.length,
+        .ptr=malloc(str.length+1)
+    };
+    str.ptr+=str.offset;
+    for(uint32 i=0; i<str.length; i++)
+        extr.ptr[i]=str.ptr[i];
+    extr.ptr[str.length]='\0';
+    return extr;
+}
+
+//compares two strings, NullPtr-friendly
+bool StringFragment_compare(StringFragment str0, StringFragment str1){
+    if(str0.length!=str1.length) return false;
+    if(!str0.ptr) return str1.ptr ? false : true;
+    else if(!str1.ptr) return false;
+    str0.ptr+=str0.offset;
+    str1.ptr+=str1.offset;
+    while(str0.length-->0)
+        if(*str0.ptr++ != *str1.ptr++) 
+            return false;
+    return true;
+}
+
+//creates new StringFragment which is reversed variant of <s>
+StringFragment StringFragment_reverse(StringFragment s){
+    if(s.length==0) return s;
+    StringFragment r={
+        .offset=0,
+        .length=s.length,
+        .ptr=malloc(s.length)
+    };
+    for(uint32 i=0; i<s.length; i++)
+        r.ptr[i+s.offset]=s.ptr[s.length-i-1];
+    return r;
+}
diff --git a/StringFragment/StringFragment.h b/StringFragment/StringFragment.h
new file mode 100644
index 0000000..9cfbcd4
--- /dev/null
+++ b/StringFragment/StringFragment.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#if __cplusplus
+extern "C" {
+#endif
+
+#include "../base/base.h"
+
+//part of string
+typedef struct StringFragment{
+    char* ptr; //may be without '\0' at the end
+    uint32 offset;
+    uint32 length;
+} StringFragment;
+
+static const StringFragment stringNull={NULL,0,0};
+
+//copies <length> characters from <ptr+offset> to new StringFragment (adding '\0' at the end)
+StringFragment StringFragment_extract(StringFragment str);
+
+//compares two strings, NullPtr-friendly
+bool StringFragment_compare(StringFragment str0, StringFragment str1);
+
+//creates new StringFragment which is reversed variant of <s>
+StringFragment StringFragment_reverse(StringFragment s);
+
+#if __cplusplus
+}
+#endif
\ No newline at end of file
diff --git a/base/base.h b/base/base.h
index ad651e6..b23b92d 100644
--- a/base/base.h
+++ b/base/base.h
@@ -7,7 +7,7 @@ extern "C" {
 #include "std.h"
 #include "types.h"
 #include "errors.h"
-#include "mystr.h"
+#include "cptr.h"
 
 // executes codeblock and prints execution time
 #ifdef CLOCK_REALTIME //non-standard high-precision clock
diff --git a/base/cptr.c b/base/cptr.c
new file mode 100644
index 0000000..0646b15
--- /dev/null
+++ b/base/cptr.c
@@ -0,0 +1,36 @@
+#include "base.h"
+
+//returns length of string (without \0)
+uint32 cptr_length(char* str){
+    uint32 len=0;
+    while(*(str++)) len++;
+    return len;
+}
+
+//allocates new char[] and copies src there
+char* cptr_copy(char* src){
+    uint32 len=cptr_length(src)+1;
+    char* dst=malloc(len);
+    while(len-->0)
+        dst[len]=src[len];
+    return dst;
+}
+
+//compares two char buffers, NullPtr-friendly
+bool cptr_compare(char* key0, char* key1){
+    if(!key0) return key1 ? false : true;
+    if(!key1) return false;
+    while(*key0&&*key1)
+        if(*key0++ != *key1++) 
+            return false;
+    return true;
+}
+
+//multiplies char n times
+char* char_multiply(char c, uint32 n){
+    char* rez=malloc(n+1);
+    rez[n]=0;
+    while(n-->0)
+        rez[n]=c;
+    return rez;
+}
\ No newline at end of file
diff --git a/base/cptr.h b/base/cptr.h
new file mode 100644
index 0000000..46f6679
--- /dev/null
+++ b/base/cptr.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#if __cplusplus
+extern "C" {
+#endif
+
+#include "types.h"
+
+//returns length of string (without \0)
+uint32 cptr_length(char* str);
+
+//allocates new char[] and copies src there
+char* cptr_copy(char* src);
+
+//compares two char buffers, NullPtr-friendly
+bool cptr_compare(char* key0, char* key1);
+
+//multiplies char n times
+char* char_multiply(char c, uint32 n);
+
+#if __cplusplus
+}
+#endif
\ No newline at end of file
diff --git a/base/errors.c b/base/errors.c
index d10d5d1..f56687a 100644
--- a/base/errors.c
+++ b/base/errors.c
@@ -1,6 +1,6 @@
 #include "std.h"
 #include "errors.h"
-#include "mystr.h"
+#include "cptr.h"
 
 char* errname(err_t err){
     switch(err){
diff --git a/base/mystr.c b/base/mystr.c
deleted file mode 100644
index 5503b46..0000000
--- a/base/mystr.c
+++ /dev/null
@@ -1,77 +0,0 @@
-#include "base.h"
-
-//returns length of string (including \0)
-uint32 cptr_length(char* str){
-    uint32 len=0;
-    while(*(str++)) len++;
-    return ++len;
-}
-
-//allocates new char[] and copies src there
-char* cptr_copy(char* src){
-    uint32 len=cptr_length(src);
-    char* dst=malloc(len*sizeof(char));
-    while(len-->0)
-        dst[len]=src[len];
-    return dst;
-}
-
-//compares two char buffers, NullPtr-friendly
-bool cptr_compare(char* key0, char* key1){
-    if(!key0) return key1 ? false : true;
-    if(!key1) return false;
-    while(*key0&&*key1)
-        if(*key0++ != *key1++) 
-            return false;
-    return true;
-}
-
-//multiplies char n times
-char* char_multiply(char c, uint32 n){
-    char* rez=malloc(n+1);
-    rez[n]=0;
-    while(n-->0)
-        rez[n]=c;
-    return rez;
-}
-
-//copies str content to new char pointer value (adding '\0' at the end)
-char* string_cpToCptr(string str){
-    if(str.length==0) return NULL;
-    char* cptr=malloc(str.length*sizeof(char)+1);
-    cptr[str.length]=0;
-    while(str.length-->0)
-        cptr[str.length]=str.ptr[str.length];
-    return cptr;
-}
-
-//copies cptr content (excluding '\0' at the end) to new string
-string string_cpFromCharPtr(char* cptr){
-    if(!cptr) return stringNull;
-    string str;
-    str.length=cptr_length(cptr)-1;
-    str.ptr=malloc(str.length);
-    for(uint32 i=0;i<str.length;i++)
-        str.ptr[i]=cptr[i];
-    return str;
-}
-
-//compares two strings, NullPtr-friendly
-bool string_compare(string str0, string str1){
-    if(str0.length!=str1.length) return false;
-    if(!str0.ptr) return str1.ptr ? false : true;
-    else if(!str1.ptr) return false;
-    while(str0.length-->0)
-        if(*str0.ptr++ != *str1.ptr++) 
-            return false;
-    return true;
-}
-
-//creates new string which is reversed variant of <s>
-string string_reverse(string s){
-    if(s.length==0) return s;
-    string r={malloc(s.length), s.length};
-    for(uint32 i=0; i<s.length; i++)
-        r.ptr[i]=s.ptr[s.length-i-1];
-    return r;
-}
diff --git a/base/mystr.h b/base/mystr.h
deleted file mode 100644
index fa95fd8..0000000
--- a/base/mystr.h
+++ /dev/null
@@ -1,44 +0,0 @@
-#pragma once
-
-#if __cplusplus
-extern "C" {
-#endif
-
-#include "types.h"
-
-//returns length of string (including \0)
-uint32 cptr_length(char* str);
-
-//allocates new char[] and copies src there
-char* cptr_copy(char* src);
-
-//compares two char buffers, NullPtr-friendly
-bool cptr_compare(char* key0, char* key1);
-
-//multiplies char n times
-char* char_multiply(char c, uint32 n);
-
-//my fixed length string struct
-//doesn't store '\0' at the end
-typedef struct string{
-    char* ptr;      //char pointer
-    uint32 length;  //amount of chars in ptr value
-} string;
-
-static const string stringNull={NULL,0};
-
-//copies str content to new char pointer value (adding '\0' at the end)
-char* string_cpToCptr(string str);
-
-//copies cptr content (excluding '\0' at the end) to new string
-string string_cpFromCharPtr(char* cptr);
-
-//compares two strings, NullPtr-friendly
-bool string_compare(string str0, string str1);
-
-//creates new string which is reversed variant of <s>
-string string_reverse(string s);
-
-#if __cplusplus
-}
-#endif
\ No newline at end of file
diff --git a/tests/main.c b/tests/main.c
index 4b3149d..6b3b54b 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -13,7 +13,7 @@ void test_all(){
 int main(){
     setlocale(LC_ALL, "en-US.Unicode");
     printf("\e[92mdtsod parser in c language!\e[97m\n");
-    optime("test_all",1,{test_all();});
+    optime("test_all",1,test_all());
     printf("\e[0m\n");
     return 0;
 }
diff --git a/tests/test_string.c b/tests/test_string.c
index e9e249f..5783047 100644
--- a/tests/test_string.c
+++ b/tests/test_string.c
@@ -1,16 +1,26 @@
 #include "tests.h"
-#include "../base/mystr.h"
+#include "../StringFragment/StringFragment.h"
 
 void test_string(){
     optime(__func__,1,({
         printf("\e[96m-------------[test_string]-------------\n");
         char c[]="0123456789abcdef";
-        string s=string_cpFromCharPtr(c);
-        printf("\e[92m\"%s\" \e[94m-> string_cpFromCharPtr()\n",c);
-        if(s.length!=16) throw("string created with incorrect length");
-        char* p=string_cpToCptr(s);
-        printf("\e[94mstring_cpToCptr() -> \e[92m\"%s\"\n",p);
-        free(p);
+
+        StringFragment s={.ptr=cptr_copy(c),.offset=0,.length=cptr_length(c)};
+        printf("\e[92m\"%s\" \e[94m-> StringFragment\n",c);
+        if(s.length!=16) throw("StringFragment created with incorrect length");
+
+        StringFragment extr=StringFragment_extract(s);
+        printf("\e[94mStringFragment_extract() -> \e[92m\"%s\"\n",extr.ptr);
+        if(extr.length!=16) throw("StringFragment extracted with incorrect length");
+        free(extr.ptr);
+
+        s.offset+=2; s.length-=4;
+        printf("\e[94mStringFragment offset+=2 length-=4\n");
+        extr=StringFragment_extract(s);
+        printf("\e[94mStringFragment_extract() ->   \e[92m\"%s\"\n",extr.ptr);
+        if(extr.length!=12) throw("StringFragment extracted with incorrect length");
         free(s.ptr);
+        free(extr.ptr);
     }));
 }
\ No newline at end of file