思想和代碼都不難，和線性表也差不多，串本來就是數據受限的線性表。

串連接：

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#include <stdio.h>
#include <string.h>
//串的定長順序存儲表示
#define MAXSTRLEN 255							//用戶可在255以內定義最大串長
typedef unsigned char SString[MAXSTRLEN + 1];	//0號單元存放串的長度int Concat(SString *T,SString S1,SString S2)//用T返回S1和S2聯接而成的新串。若未截斷返回1，若截斷返回0
{int i = 1,j,uncut = 0;if(S1[0] + S2[0] <= MAXSTRLEN)	//未截斷{for (i = 1; i <= S1[0]; i++)//賦值時等號不可丟(*T)[i] = S1[i];for (j = 1; j <= S2[0]; j++)(*T)[S1[0]+j] = S2[j];	//(*T)[i+j] = S2[j](*T)[0] = S1[0] + S2[0];uncut = 1;}else if(S1[0] < MAXSTRLEN)		//截斷{for (i = 1; i <= S1[0]; i++)//賦值時等號不可丟(*T)[i] = S1[i];for (j = S1[0] + 1; j <= MAXSTRLEN; j++){(*T)[j] = S2[j - S1[0] ];(*T)[0] = MAXSTRLEN;uncut = 0;}}else{for (i = 0; i <= MAXSTRLEN; i++)(*T)[i] = S1[i];/*或者分開賦值，先賦值內容，再賦值長度for (i = 1; i <= MAXSTRLEN; i++)(*T)[i] = S1[i];(*T)[0] = MAXSTRLEN;*/uncut = 0;}return uncut;
}int SubString(SString *Sub,SString S,int pos,int len)//用Sub返回串S的第pos個字符起長度為len的子串//其中，1 ≤ pos ≤ StrLength(S)且0 ≤ len ≤ StrLength(S) - pos + 1(從pos開始到最后有多少字符)//第1個字符的下標為1,因為第0個字符存放字符長度
{int i;if(pos < 1 || pos > S[0] || len < 0 || len > S[0] - pos + 1)return 0;for (i = 1; i <= len; i++){//S中的[pos,len]的元素 -> *Sub中的[1,len](*Sub)[i] = S[pos + i - 1];//下標運算符 > 尋址運算符的優先級}(*Sub)[0] = len;return 1;
}
void PrintStr(SString S)
{int i;for (i = 1; i <= S[0]; i++)printf("%c",S[i]);printf("\n");
}int main(void)
{/*定長順序存儲初始化和打印的方法SString s = {4,'a','b','c','d'};int i;//s = "abc";	//不可直接賦值for (i = 1; i <= s[0]; i++)printf("%c",s[i]);*/SString s1 = {4,'a','b','c','d'};SString s2 = {4,'e','f','g','h'},s3;SString T,Sub;int i;for (i = 1; i <= 255; i++){s3[i] = 'a';if(i >= 248)s3[i] = 'K';}s3[0] = 255;SubString(&Sub,s3,247,8);PrintStr(Sub);return 0;
}

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