P86 例4-2 编写一个程序，测试上述动态数组存储结构下串操作函数的正确性。
书上的头文件DString.h错误，配合源文件例4-2.c，过不了VS2019（64位）的编译，正确的头文件DString.h如下：
头文件：DString.h
#include<stdio.h> #include<stdlib.h> #include<string.h> typedef struct { char* str; int maxLength; int length; }DString; void Initiate(DString* S, int max, char* string) { int i; int size = max + 1; S->str = (char*)malloc(sizeof(char) * size); if (S->str != NULL) { S->maxLength = max; S->length = (int)strlen(string); for (i = 0; i < S->length; i++) S->str[i] = string[i]; S->str[i] = '\0'; } } int Insert(DString* S, int pos, DString T) { if (pos < 0) { printf("参数pos出错！"); return 0; } else { int i; char* buffer = (char*)malloc(sizeof(char) * (S->length + 1)); buffer[S->length] = '\0'; for (i = 0; i < S->length; i++) { buffer[i] = S->str[i]; } if (S->length + T.length > S->maxLength) { free(S->str); int size = S->length + T.length + 1; S->str = (char*)malloc(sizeof(char) * size); S->str[size - 1] = '\0'; S->maxLength = S->length + T.length; } for (i = S->length - 1; i >= pos; i--) S->str[i + T.length] = buffer[i]; for (i = 0; i < T.length; i++) S->str[pos + i] = T.str[i]; S->length += T.length; S->str[S->length + T.length] = '\0'; free(buffer); return 1; } } int Delete(DString* S, int pos, int len) { int i; if (S->length <= 0) { printf("数组中未存放字符无元素可删！\n"); return 0; } else if (pos < 0 || len<0 || pos + len>S->length) { printf("参数pos和len不合法！\n"); return 0; } else { for (i = pos + len; i <= S->length - 1; i++) S->str[i - len] = S->str[i]; S->length = S->length - len; return 1; } } int SubString(DString* S, int pos, int len, DString* T) { int i; if (pos < 0 || len<0 || pos + len>S->length) { printf("参数pos和len出错!\n"); return 0; } if (len > T->maxLength) { T->str = (char*)malloc((len + 1) * sizeof(char)); T->maxLength = len; } for (i = 0; i < len; i++) T->str[i] = S->str[pos + i]; T->length = len; T->str[i] = '\0'; return 1; } void Destroy(DString* S) { free(S->str); S->maxLength = 0; S->length = 0; }源文件：例4-2.c
#include"DString.h" int main() { DString myString1,myString2,myString3; int i,max1=5,max2=9,max3=0; Initiate(&myString1,max1,"Data "); Initiate(&myString2,max2,"Structure"); Initiate(&myString3,max3,""); printf("初始myString2串: "); for(i=0;i<myString2.length;i++) printf("%c",myString2.str[i]); printf(" maxLength=%d",myString2.maxLength); printf(" length=%d\n",myString2.length); //测试插入函数 Insert(&myString2,0,myString1); printf("插入子串后myString2串: "); for(i=0;i<myString2.length;i++) printf("%c",myString2.str[i]); printf(" maxLength=%d",myString2.maxLength); printf(" length=%d\n",myString2.length); //测试删除函数 Delete(&myString2,0,5); printf("删除子串后myString2串: "); for(i=0;i<myString2.length;i++) printf("%c",myString2.str[i]); printf(" maxLength=%d",myString2.maxLength); printf(" length=%d\n",myString2.length); //测试取子串函数 SubString(&myString2,0,5,&myString3); printf("取子串后myString3串: "); for(i=0;i<myString3.length;i++) printf("%c",myString3.str[i]); printf(" maxLength=%d",myString3.maxLength); printf(" length=%d\n",myString3.length); //测试撤销函数 Destroy(&myString1); Destroy(&myString2); Destroy(&myString3); return 0; }