C语言写的字符串常用操作API:包括创建,销毁,插入,删除,替换,拷贝,合并,连接,子串的定位,最大子串的查找。
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//字符串的实现
/*这里选用的是线性分配存储的字符串形式,主要是为了可以不限定字符串长度*/
#pragma warning(disable:4996)
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAXSTRELEN 255
typedef struct {
char ch[MAXSTRELEN];
int length;
}SString;
//字符串初始化,同时也可以通过初始化来将字符串销毁,重新赋值
InitStr(SString* string) {
for (int i = 0; i < MAXSTRELEN; i++) {
(*string).ch[i] = '\0';
}
(*string).length = 0;
}
//字符串常量复制得到字符串
CreateString(SString *string, char *ch) {
unsigned int i = 0;
int length = StrLength(*string);
while (i<strlen(ch))
{
(*string).ch[i+length] = ch[i];
(*string).length++;
i++;
}
}
//非初始化创建字符串
CreateString2(SString *string, char *ch,int pos,int n) {
unsigned int i = 0;
int length = StrLength(*string);
while (i< n)
{
(*string).ch[i+length] = ch[i+pos];
(*string).length++;
i++;
}
}
//字符串S的第pos个位置开始复制n个自负到字符串string
StrCat(SString *string, SString S, int pos ,int n) {
CreateString2(string, S.ch, pos, n);
}
//字符串遍历
StrTraversal(SString string) {
printf("%s\n", string.ch);
}
//字符串长度
int StrLength(SString string) {
return string.length;
}
//字符串为空
int StrEmpty(SString string) {
return string.length ? string.length :0 ;
}
//如果string>s则返回正数,小于返回负数,相等返回0
int StrCompare(SString string, SString s) {
int length_a = StrLength(string);
int length_b = StrLength(s);
int length = max(length_a, length_b);
for (int i = 0; i <length; i++) {
if (string.ch[i] != s.ch[i]) {
return string.ch[i]- s.ch[i];
break;
}
}
return 0;
}
//两个字符串连接成一个字符串
Concat(SString *string, SString S1, SString S2) {
int length = S1.length + S2.length;
StrCat(string, S1,0,S1.length);
(*string).length = length;
for (int i = 0; i < S2.length; i++) {
(*string).ch[S1.length + i] = S2.ch[i];
}
}
//用Sub返回S的第pos字自符起长度为len的子串
SubString(SString *Sub, SString string, int pos, int len) {
for (int i = 0; i < len; i++) {
(*Sub).ch[i] = string.ch[i + pos];
(*Sub).length = len;
}
}
//求子串位置的定位函数
/*
pos表示匹配串第pos位之后,pos和返回值均从0计数
*/
int SubIndex(SString string, SString Sub, int pos) {
int i = pos, j = 0;
for (; i < StrLength(string) && j < StrLength(Sub);) {
if (Sub.ch[j] == string.ch[i]) {
j++;
i++;
}
else {
i++;
j = 0;
}
}
//return i;
if (j == StrLength(Sub))
return i-StrLength(Sub);
else return -1;
}
//用V替换S中所有与T相等的不重叠的子串
StrReplace(SString*S, SString T, SString V,SString*D,int pi) {
//例子: S:HELLOWORLD T:LLOW V:HELL
//首先获取字符串S中T的索引
//SString D;
//InitStr(&D);
int slength = StrLength(*S);
// 计算被替换串和替换串的长度.
int nsrclen = StrLength(T);
int nDstLen = StrLength(V);
int nLen ;
//S的合并起始点地址
//int pi = 0;
int p = SubIndex(*S, T, pi);
if (p)
{
//如果找到
//计算被替换串前边字符串的长度.
nLen = (p - pi);
StrCat(D,*S,pi,nLen);
StrCat(D, V, 0, nDstLen);
//StrCat(&D, T, p + nsrclen,nsrclen-p-pi);
pi = p+nsrclen;
StrReplace(S,T,V,D,pi);
}
else {
StrCat(D, *S, pi, slength - pi);
}
StrTraversal(*D);
}
/*在字符串的S的第pos个位置插入字符串T,并用S返回插入后的字符串*/
StrInsert(SString*S, SString T, int pos) {
SString tmp;
InitStr(&tmp);
StrCat(&tmp, *S, 0, pos);
StrCat(&tmp, T, 0, StrLength(T));
StrCat(&tmp,*S,pos,StrLength(*S)-pos);
//先将串S销毁,然后再将串tmp复制到串S
InitStr(S);
StrCat(S, tmp, 0, StrLength(tmp));
}
//删除pos个位置开始的len长度的字符串,并返回到S中
StrRemove(SString*S, int pos, int len) {
SString tmp;
InitStr(&tmp);
StrCat(&tmp, *S, 0, pos);
StrCat(&tmp, *S, pos+len, StrLength(*S) - pos);
//先将串S销毁,然后再将串tmp复制到串S
InitStr(S);
StrCat(S, tmp, 0, StrLength(tmp));
}
//两个字符串的最长子串,src为源字符串,string为匹配字符串,max_length_substring为返回的最长子字符串
int MaxLengthSubString(SString src,SString string,SString *maxsubstring) {
int index;
for (int j = StrLength(string); j > 0; j--) {
for (int i = 0; i < j; i++) {
SString sub;
InitStr(&sub);
SubString(&sub, string, i, j - i);
index = SubIndex(src,sub,0);
if (index >=0) {
StrCat(maxsubstring, sub, 0, StrLength(sub));
//StrTraversal(sub);
return 0;//返回0表示找到
}
}
}
return -1;//返回-1表示为匹配
}
int main(void) {
SString string,s,slast,LAST;
//初始化部分
InitStr(&string);
//字符串初始化必须分配内存空间;或者用char[],这样直接保存在栈区不用malloc内存空间
char ch[MAXSTRELEN];
scanf("%s", ch);
CreateString(&string, ch);
//初始化部分
InitStr(&s);
//字符串初始化必须分配内存空间;或者用char[],这样直接保存在栈区不用malloc内存空间
char character[MAXSTRELEN];
scanf("%s", character);
CreateString(&s, character);
//两字符串最长公共子串
SString maxsubstring;
InitStr(&maxsubstring);
int tmps =MaxLengthSubString(string, s, &maxsubstring);
if (tmps == 0) {
StrTraversal(maxsubstring);
}
else {
printf("no common str");
}
////初始化部分
//InitStr(&slast);
////字符串初始化必须分配内存空间;或者用char[],这样直接保存在栈区不用malloc内存空间
//char character2[MAXSTRELEN];
//scanf("%s", character2);
//CreateString(&slast, character2);
//InitStr(&LAST);
SString tmp;
InitStr(&tmp);
////字符串的删除
//StrRemove(&string, 2, 3);
//StrTraversal(string);
//字符串的插入
//StrInsert(&string, s, 2);
//StrTraversal(string);
////获取子串
//SString sub;
//InitStr(&sub);
////获取子串
//SubString(&sub, string, 0, 3);
//
////字符串遍历
//StrTraversal(string);
//StrTraversal(sub);
///*两字符串合并保存在slast中*/
//Concat(&slast, string,s);
//StrTraversal(slast);
///*字符串拷贝到string中*/
//StrCat(&string, s,0,s.length);
//printf("%s\n", string.ch);
//printf("%d\n", string.length);
///*字符串比较*/
//int tmp=StrCompare(string, s);
/*字符串替换*/
//StrReplace(&string, s, slast, &LAST,0);
//子串索引位置
/*int tmp = SubIndex(string, s,0);
printf("%d\n", tmp);*/
}