diff --git a/_03.串/01串_String.c b/_03.串/01串_String.c
deleted file mode 100644
index db9b232..0000000
--- a/_03.串/01串_String.c
+++ /dev/null
@@ -1,318 +0,0 @@
-#include "string.h"
-#include "stdio.h"    
-#include "stdlib.h"   
-#include "io.h"  
-#include "math.h"  
-#include "time.h"
-
-#define OK 1
-#define ERROR 0
-#define TRUE 1
-#define FALSE 0
-
-#define MAXSIZE 40 /* ´æ´¢¿Õ¼ä³õʼ·ÖÅäÁ¿ */
-
-typedef int Status;		/* StatusÊǺ¯ÊýµÄÀàÐÍ,ÆäÖµÊǺ¯Êý½á¹û״̬´úÂ룬ÈçOKµÈ */
-typedef int ElemType;	/* ElemTypeÀàÐ͸ù¾Ýʵ¼ÊÇé¿ö¶ø¶¨£¬ÕâÀï¼ÙÉèΪint */
-
-typedef char String[MAXSIZE+1]; /*  0ºÅµ¥Ôª´æ·Å´®µÄ³¤¶È */
-
-/* Éú³ÉÒ»¸öÆäÖµµÈÓÚcharsµÄ´®T */
-Status StrAssign(String T,char *chars)
-{ 
-	int i;
-	if(strlen(chars)>MAXSIZE)
-		return ERROR;
-	else
-	{
-		T[0]=strlen(chars);
-		for(i=1;i<=T[0];i++)
-			T[i]=*(chars+i-1);
-		return OK;
-	}
-}
-
-/* ÓÉ´®S¸´ÖƵô®T */
-Status StrCopy(String T,String S)
-{ 
-	int i;
-	for(i=0;i<=S[0];i++)
-		T[i]=S[i];
-	return OK;
-}
-
-/* ÈôSΪ¿Õ´®,Ôò·µ»ØTRUE,·ñÔò·µ»ØFALSE */
-Status StrEmpty(String S)
-{ 
-	if(S[0]==0)
-		return TRUE;
-	else
-		return FALSE;
-}
-
-/*  ³õʼÌõ¼þ: ´®SºÍT´æÔÚ */
-/*  ²Ù×÷½á¹û: ÈôS>T,Ôò·µ»ØÖµ>0;ÈôS=T,Ôò·µ»ØÖµ=0;ÈôS<T,Ôò·µ»ØÖµ<0 */
-int StrCompare(String S,String T)
-{ 
-	int i;
-	for(i=1;i<=S[0]&&i<=T[0];++i)
-		if(S[i]!=T[i])
-			return S[i]-T[i];
-	return S[0]-T[0];
-}
-
-/* ·µ»Ø´®µÄÔªËظöÊý */
-int StrLength(String S)
-{ 
-	return S[0];
-}
-
-/* ³õʼÌõ¼þ:´®S´æÔÚ¡£²Ù×÷½á¹û:½«SÇåΪ¿Õ´® */
-Status ClearString(String S)
-{ 
-	S[0]=0;/*  Áî´®³¤ÎªÁã */
-	return OK;
-}
-
-/* ÓÃT·µ»ØS1ºÍS2Áª½Ó¶ø³ÉµÄд®¡£Èôδ½Ø¶Ï£¬Ôò·µ»ØTRUE£¬·ñÔòFALSE */
-Status Concat(String T,String S1,String S2)
-{
-	int i;
-	if(S1[0]+S2[0]<=MAXSIZE)
-	{ /*  δ½Ø¶Ï */
-		for(i=1;i<=S1[0];i++)
-			T[i]=S1[i];
-		for(i=1;i<=S2[0];i++)
-			T[S1[0]+i]=S2[i];
-		T[0]=S1[0]+S2[0];
-		return TRUE;
-	}
-	else
-	{ /*  ½Ø¶ÏS2 */
-		for(i=1;i<=S1[0];i++)
-			T[i]=S1[i];
-		for(i=1;i<=MAXSIZE-S1[0];i++)
-			T[S1[0]+i]=S2[i];
-		T[0]=MAXSIZE;
-		return FALSE;
-	}
-}
-
-/* ÓÃSub·µ»Ø´®SµÄµÚpos¸ö×Ö·ûÆ𳤶ÈΪlenµÄ×Ó´®¡£ */
-Status SubString(String Sub,String S,int pos,int len)
-{
-	int i;
-	if(pos<1||pos>S[0]||len<0||len>S[0]-pos+1)
-		return ERROR;
-	for(i=1;i<=len;i++)
-		Sub[i]=S[pos+i-1];
-	Sub[0]=len;
-	return OK;
-}
-
-/* ·µ»Ø×Ó´®TÔÚÖ÷´®SÖеÚpos¸ö×Ö·ûÖ®ºóµÄλÖá£Èô²»´æÔÚ,Ôòº¯Êý·µ»ØֵΪ0¡£ */
-/* ÆäÖÐ,T·Ç¿Õ,1¡Üpos¡ÜStrLength(S)¡£ */
-int Index(String S, String T, int pos) 
-{
-	int i = pos;	/* iÓÃÓÚÖ÷´®SÖе±Ç°Î»ÖÃϱêÖµ£¬Èôpos²»Îª1£¬Ôò´ÓposλÖÿªÊ¼Æ¥Åä */
-	int j = 1;				/* jÓÃÓÚ×Ó´®TÖе±Ç°Î»ÖÃϱêÖµ */
-	while (i <= S[0] && j <= T[0]) /* ÈôiСÓÚSµÄ³¤¶È²¢ÇÒjСÓÚTµÄ³¤¶Èʱ£¬Ñ­»·¼ÌÐø */
-	{
-		if (S[i] == T[j]) 	/* Á½×ÖĸÏàµÈÔò¼ÌÐø */
-      	{
-			++i;
-         	++j; 
-      	} 
-      	else 				/* Ö¸ÕëºóÍËÖØпªÊ¼Æ¥Åä */
-      	{  
-         	i = i-j+2;		/* iÍ˻ص½ÉÏ´ÎÆ¥ÅäÊ×λµÄÏÂһλ */
-         	j = 1; 			/* jÍ˻ص½×Ó´®TµÄÊ×λ */
-      	}      
-	}
-	if (j > T[0]) 
-		return i-T[0];
-	else 
-		return 0;
-}
-
-
-/*  TΪ·Ç¿Õ´®¡£ÈôÖ÷´®SÖеÚpos¸ö×Ö·ûÖ®ºó´æÔÚÓëTÏàµÈµÄ×Ó´®£¬ */
-/*  Ôò·µ»ØµÚÒ»¸öÕâÑùµÄ×Ó´®ÔÚSÖеÄλÖ㬷ñÔò·µ»Ø0 */
-int Index2(String S, String T, int pos) 
-{
-	int n,m,i;
-	String sub;
-	if (pos > 0) 
-	{
-		n = StrLength(S);	/* µÃµ½Ö÷´®SµÄ³¤¶È */
-		m = StrLength(T);	/* µÃµ½×Ó´®TµÄ³¤¶È */
-		i = pos;
-		while (i <= n-m+1) 
-		{
-			SubString (sub, S, i, m);	/* È¡Ö÷´®ÖеÚi¸öλÖó¤¶ÈÓëTÏàµÈµÄ×Ó´®¸øsub */
-			if (StrCompare(sub,T) != 0)    /* Èç¹ûÁ½´®²»ÏàµÈ */
-				++i;
-			else 				/* Èç¹ûÁ½´®ÏàµÈ */
-				return i;		/* Ôò·µ»ØiÖµ */
-		}
-	}
-	return 0;	/* ÈôÎÞ×Ó´®ÓëTÏàµÈ£¬·µ»Ø0 */
-}
-
-
-/*  ³õʼÌõ¼þ: ´®SºÍT´æÔÚ,1¡Üpos¡ÜStrLength(S)+1 */
-/*  ²Ù×÷½á¹û: ÔÚ´®SµÄµÚpos¸ö×Ö·û֮ǰ²åÈë´®T¡£ÍêÈ«²åÈë·µ»ØTRUE,²¿·Ö²åÈë·µ»ØFALSE */
-Status StrInsert(String S,int pos,String T)
-{ 
-	int i;
-	if(pos<1||pos>S[0]+1)
-		return ERROR;
-	if(S[0]+T[0]<=MAXSIZE)
-	{ /*  ÍêÈ«²åÈë */
-		for(i=S[0];i>=pos;i--)
-			S[i+T[0]]=S[i];
-		for(i=pos;i<pos+T[0];i++)
-			S[i]=T[i-pos+1];
-		S[0]=S[0]+T[0];
-		return TRUE;
-	}
-	else
-	{ /*  ²¿·Ö²åÈë */
-		for(i=MAXSIZE;i<=pos;i--)
-			S[i]=S[i-T[0]];
-		for(i=pos;i<pos+T[0];i++)
-			S[i]=T[i-pos+1];
-		S[0]=MAXSIZE;
-		return FALSE;
-	}
-}
-
-/*  ³õʼÌõ¼þ: ´®S´æÔÚ,1¡Üpos¡ÜStrLength(S)-len+1 */
-/*  ²Ù×÷½á¹û: ´Ó´®SÖÐɾ³ýµÚpos¸ö×Ö·ûÆ𳤶ÈΪlenµÄ×Ó´® */
-Status StrDelete(String S,int pos,int len)
-{ 
-	int i;
-	if(pos<1||pos>S[0]-len+1||len<0)
-		return ERROR;
-	for(i=pos+len;i<=S[0];i++)
-		S[i-len]=S[i];
-	S[0]-=len;
-	return OK;
-}
-
-/*  ³õʼÌõ¼þ: ´®S,TºÍV´æÔÚ,TÊÇ·Ç¿Õ´®£¨´Ëº¯ÊýÓë´®µÄ´æ´¢½á¹¹Î޹أ© */
-/*  ²Ù×÷½á¹û: ÓÃVÌæ»»Ö÷´®SÖгöÏÖµÄËùÓÐÓëTÏàµÈµÄ²»ÖصþµÄ×Ó´® */
-Status Replace(String S,String T,String V)
-{ 
-	int i=1; /*  ´Ó´®SµÄµÚÒ»¸ö×Ö·ûÆð²éÕÒ´®T */
-	if(StrEmpty(T)) /*  TÊÇ¿Õ´® */
-		return ERROR;
-	do
-	{
-		i=Index(S,T,i); /*  ½á¹ûiΪ´ÓÉÏÒ»¸öiÖ®ºóÕÒµ½µÄ×Ó´®TµÄλÖà */
-		if(i) /*  ´®SÖдæÔÚ´®T */
-		{
-			StrDelete(S,i,StrLength(T)); /*  ɾ³ý¸Ã´®T */
-			StrInsert(S,i,V); /*  ÔÚÔ­´®TµÄλÖòåÈë´®V */
-			i+=StrLength(V); /*  ÔÚ²åÈëµÄ´®VºóÃæ¼ÌÐø²éÕÒ´®T */
-		}
-	}while(i);
-	return OK;
-}
-
-/*  Êä³ö×Ö·û´®T */
-void StrPrint(String T)
-{ 
-	int i;
-	for(i=1;i<=T[0];i++)
-		printf("%c",T[i]);
-	printf("\n");
-}
-
-
-int main()
-{
-	
-	int i,j;
-	Status k;
-	char s;
-	String t,s1,s2;
-	printf("ÇëÊäÈë´®s1: ");
-	
-	k=StrAssign(s1,"abcd");
-	if(!k)
-	{
-		printf("´®³¤³¬¹ýMAXSIZE(=%d)\n",MAXSIZE);
-		exit(0);
-	}
-	printf("´®³¤Îª%d ´®¿Õ·ñ£¿%d(1:ÊÇ 0:·ñ)\n",StrLength(s1),StrEmpty(s1));
-	StrCopy(s2,s1);
-	printf("¿½±´s1Éú³ÉµÄ´®Îª: ");
-	StrPrint(s2);
-	printf("ÇëÊäÈë´®s2: ");
-	
-	k=StrAssign(s2,"efghijk");
-	if(!k)
-	{
-		printf("´®³¤³¬¹ýMAXSIZE(%d)\n",MAXSIZE);
-		exit(0);
-	}
-	i=StrCompare(s1,s2);
-	if(i<0)
-		s='<';
-	else if(i==0)
-		s='=';
-	else
-		s='>';
-	printf("´®s1%c´®s2\n",s);
-	k=Concat(t,s1,s2);
-	printf("´®s1Áª½Ó´®s2µÃµ½µÄ´®tΪ: ");
-	StrPrint(t);
-	if(k==FALSE)
-		printf("´®tÓнضÏ\n");
-	ClearString(s1);
-	printf("ÇåΪ¿Õ´®ºó,´®s1Ϊ: ");
-	StrPrint(s1);
-	printf("´®³¤Îª%d ´®¿Õ·ñ£¿%d(1:ÊÇ 0:·ñ)\n",StrLength(s1),StrEmpty(s1));
-	printf("Çó´®tµÄ×Ó´®,ÇëÊäÈë×Ó´®µÄÆðʼλÖÃ,×Ó´®³¤¶È: ");
-
-	i=2;
-	j=3;
-	printf("%d,%d \n",i,j);
-
-	k=SubString(s2,t,i,j);
-	if(k)
-	{
-		printf("×Ó´®s2Ϊ: ");
-		StrPrint(s2);
-	}
-	printf("´Ó´®tµÄµÚpos¸ö×Ö·ûÆð,ɾ³ýlen¸ö×Ö·û£¬ÇëÊäÈëpos,len: ");
-	
-	i=4;
-	j=2;
-	printf("%d,%d \n",i,j);
-
-
-	StrDelete(t,i,j);
-	printf("ɾ³ýºóµÄ´®tΪ: ");
-	StrPrint(t);
-	i=StrLength(s2)/2;
-	StrInsert(s2,i,t);
-	printf("ÔÚ´®s2µÄµÚ%d¸ö×Ö·û֮ǰ²åÈë´®tºó,´®s2Ϊ:\n",i);
-	StrPrint(s2);
-	i=Index(s2,t,1);
-	printf("s2µÄµÚ%d¸ö×ÖĸÆðºÍtµÚÒ»´ÎÆ¥Åä\n",i);
-	SubString(t,s2,1,1);
-	printf("´®tΪ£º");
-	StrPrint(t);
-	Concat(s1,t,t);
-	printf("´®s1Ϊ£º");
-	StrPrint(s1);
-	Replace(s2,t,s1);
-	printf("Óô®s1È¡´ú´®s2Öкʹ®tÏàͬµÄ²»ÖصþµÄ´®ºó,´®s2Ϊ: ");
-	StrPrint(s2);
-
-
-	return 0;
-}
-
diff --git a/_03.串/_a.串.c b/_03.串/_a.串.c
index cb083ac..6943cfa 100644
--- a/_03.串/_a.串.c
+++ b/_03.串/_a.串.c
@@ -2,7 +2,7 @@
  * @Author: Xu Bai
  * @Date: 2019-07-06 22:20:08
  * @LastEditors: Xu Bai
- * @LastEditTime: 2019-07-07 23:58:05
+ * @LastEditTime: 2019-07-08 00:10:40
  */
 
 #include "string.h"
@@ -309,10 +309,34 @@ int main()
         printf("ERROR!\n");
         exit(0);
     }
-    StrPrint("s1=%s \n",s1);
-    StrCopy(s2,s1);
-    printf("copyed s2=%s \n",s2);
-
+    printf("s1= ");
+    StrPrint(s1);
+    StrCopy(s2, s1);
+    printf("s2= ");
+    StrPrint(s2);
+    StrAssign(s2, "-------");
+    printf("then, s2= ");
+    StrPrint(s2);
+    String t;
+    k = Concat(t, s1, s2);
+    if (k)
+    {
+        printf("concat completed: ");
+        StrPrint(t);
+    }
+    else
+    {
+        printf("cutted off:");
+        StrPrint(t);
+    }
+    int i = 2, j = 3;
+    k = SubString(s2, t, i, j);
+    printf("Substring: ");
+    StrPrint(s2);
+    StrDelete(t, 1, 2);
+    StrInsert(t, 1, s2);
+    Replace(s2, t, s1);
+    StrPrint(s2);
     getchar();
     return OK;
 }
\ No newline at end of file
diff --git a/a.out b/a.out
index 86c558f..8e41c6f 100644
Binary files a/a.out and b/a.out differ