Preliminary understanding of string

One 、 Related concepts of string

1、 Definition of string ： A finite sequence of zero or more arbitrary characters .

2、 Empty string is generally used ∅ Express .

3、 The strings are equal : If and only if the length of two strings is equal and At each corresponding position The characters of are the same , The two strings are equal . All empty strings are equal .

4、 Type definition of string ：

ADT String {

Data objects :.......

Data relation :.......

Basic operation :

(1) StrAssign (&T,chars)                        // String assignment

(2) StrCompare (S,T)                           // String comparison

(3) StrLength (S)                                 // Find the length of the string

(4) Concat(&T,S1,S2)                        // String connection

(5) SubString(&Sub,S,pos,len)         // substring

(6) StrCopy(&T,S)                           // String copy

(7) StrEmpty(S)                               // The string is empty

(8) ClearString (&S)                       // Empty string

(9) Index(S,T,pos)                         // The position of the substring

(11) Replace(&S,T,V)                    // String replacement

(12) Strlnsert(&S,pos,T)                  // Substring insertion

(12) StrDelete(&S,pos,len)              // Substring deletion

(13) DestroyString(&S)                   // String destruction

}ADT String

Two 、 String storage structure

1、 Chain storage structure of string —— Block chain structure

#define CHUNKSIZE 80                // The size of the block can be defined by the user 
typedef struct Chunk{

char ch[CHUNKSIZE];

struct Chunk *next;

}Chunk;

typedef struct{

Chunk *head,*tail;           // The head and tail pointers of the string 

int curlen;                 // The current length of the string 

}LString;                  // Block chain structure of string 

2、 The sequential storage structure of a string

#define MAXLEN 255

typedef struct{

char ch[MAXLEN+1];            // A one-dimensional array of storage strings 
int length;                  // The current length of the string 

}SString;