Data Structure Learning (10)-string operations

I haven't read the data structure for a few days. Today I started again.

A string is a special linear table. Each node of a string is a character. Therefore, a string is also called a string.

The operations on strings mainly include determining the length of strings, copying strings, connecting strings, seeking substrings, inserting strings, deleting strings, and locating substrings. String operations are also a common part of the C language test.

The following code implements the main operations on strings.

# Include <stdio. h> # include <stdlib. h> # define maxsize 20 char * string_create (); // create the int string_length (char * s); // obtain the string length void string_show (char * s ); // output string char * string_copy (char * D, char * s); // string copy char * string_connect (char * D, char * s ); // string connection char * string_substr (char * D, char * s, int POs, int Len); // obtain the substring int string_compare (char * D, char * s ); // string comparison char * string_insert (char * D, char * s, int POS); // string insertion char * string_del Ete (char * D, int POs, int Len); // Delete int string_index (char * D, char * s, int POS ); // String Match int main (void) {int choice; char * STR, * C; int ans, POs, Len; C = (char *) malloc (sizeof (maxsize); printf ("enter a string (less than 10 characters): \ n"); STR = string_create (); While (1) {printf ("*************************** \ n "); printf ("string operation exercise: \ n"); printf ("1. string Length \ n "); printf (" 2. string replication \ n "); printf (" 3. string connection \ n "); printf (" 4. substring \ n "); printf (" 5. comparison string \ n "); printf (" 6. String insertion \ n "); printf (" 7. string deletion \ n "); printf (" 8. string positioning \ n "); printf (" 9. string output \ n "); printf (" 10. exit program \ n "); printf (" input select: \ n "); scanf (" % d ", & choice); getchar (); Switch (choice) {Case 1: ANS = string_length (STR); printf ("the string length is % d \ n", ANS); break; Case 2: c = string_copy (C, str); printf ("target string: \ n"); string_show (c); break; Case 3: printf ("input string (less than 10 characters) \ n "); gets (c); C = string_connect (C, STR); printf (" the new string is \ n "); string_show (c); break; case 4: PRI Ntf ("Enter the position and length of the substring \ n"); scanf ("% d", & Pos, & Len); C = string_substr (C, STR, POs, Len); If (C = NULL) printf ("failed to request the substring! \ N "); else {printf (" the substring is \ n "); string_show (c) ;}break; Case 5: printf (" input string: \ n "); gets (c); ans = string_compare (C, STR); If (ANS> 0) printf (" the first string is large \ n "); else if (ANS <0) printf ("the second string is large \ n"); elseprintf ("the two strings are equal \ n"); break; Case 6: printf ("input string to be inserted in the main string \ n"); gets (c); printf ("input insert position: \ n "); scanf ("% d", & Pos); STR = string_insert (STR, C, POS); printf ("New String: \ n"); string_show (STR ); break; Case 7: printf ("Enter the start position and length of the substring \ n"); scanf ("% d % D ", & Pos, & Len); STR = string_delete (STR, POs, Len); break; case 8: printf (" Enter the substring to be located: \ n "); gets (c); ans = string_index (STR, C, 1); printf (" the result is % d \ n ", ANS); break; case 9: string_show (STR); break; case 10: Return 0; break; default: printf ("the selection is invalid! \ N "); break ;}} return 1 ;}// create a string of char * string_create () {char * s, ch; int I = 0; S = (char *) malloc (maxsize); CH = getchar (); While (Ch! = '#') {* (S + I) = CH; I ++; CH = getchar ();} if (I> maxsize/2) printf ("the input length is greater than 10! \ N "); else * (S + I) = '\ 0'; return s;} // returns the string length int string_length (char * s) {int L = 0; while (* s! = '\ 0') {L ++; s ++;} return l ;}// copy a string of char * string_copy (char * D, char * s) {char * C; C = D; while (* D ++ = * s ++ )! = '\ 0'); Return C;} // string connection char * string_connect (char * D, char * s) {char * C; int L, I = 0 ;; C = D; L = string_length (d); D = d + L; while (* D ++ = * s ++ )! = '\ 0'); // returns C;} // returns the substring char * string_substr (char * D, char * s, int POs, int Len) {char * C1, * C2 = NULL; int L, I; C2 = (char *) malloc (maxsize/2); C1 = s; D = c2; L = string_length (s); If (Pos> L | POS <1) // return NULL is invalid in the input position; if (LEN <0) // return NULL is invalid in the input length; c1 = C1 + pos-1; for (I = 1; I <= Len & * C1! = '\ 0'; I ++) // evaluate the string {* C2 ++ = * C1 ++;} * C2 =' \ 0 '; // do not forget the end symbol return D;} // string comparison int string_compare (char * D, char * s) {char * C1, * C2; C1 = D; c2 = s; while (* C1! = '\ 0' | * C2! = '\ 0') {If (* C1> * C2) return 1; else if (* C1 <* C2) Return-1; C1 ++; C2 ++ ;} if (* C1 = '\ 0' & * C2 =' \ 0') // when both ends, the two strings are equal and return 0; else if (* C2 = '\ 0') // The second string ends first, then the first string returns 1; elsereturn-1 ;} // insert string char * string_insert (char * D, char * s, int POS) {int I, LD, ls; char * C1, * C2; C1 = D; c2 = s; LD = string_length (d); LS = string_length (s); for (I = LD; I> = pos-1; I --) // string move back, leave the position of the string to be inserted * (C1 + LS + I) = * (C1 + I); for (I = Pos; I <= POS + ls-1; I ++) // Insert the sub-string * (C1 + I-1) = * C2 ++; * (C1 + LD + ls) = '\ 0 '; // The last ending symbol cannot forget return D;} // delete a char * string_delete (char * D, int POs, int Len) {int I, L; L = string_length (d); If (Pos + Len> L) // If the delete length is greater than the length after the start position of the string, then only keep the main string before the character * (D + pos-1) = '\ 0'; else {for (I = POS + len-1; I <= L; I ++) * (D + I-len) = * (D + I); * (D + L-len) = '\ 0'; // end character} return D ;} // locate the int string_index (char * D, char * s, int POS) of the substring {int I = pos-1, j = 0, LD, ls, B = 0; LD = string_length (d); LS = string_length (s); While (I <LD & J <ls) {If (* (D + I) = * (S + J) // if the current character is equal, {I ++; j ++ ;} else // next match {I = I-j + 1; j = 0 ;}} if (j = ls) // return (I-LS + 1); elsereturn 0;} // output string void string_show (char * s) {While (putchar (* s ++ )); printf ("\ n ");}

The above code is related to the string operation.