#include <iostream>
using namespace std;
#define MaxSize 50

typedef char ElemType;
typedef struct {
	char data[MaxSize];
	int length;
} SqString;
SqString sqStr, matchStr;
void create(SqString &s, char cstr[]) {
	int i = 0;
	for (i = 0; cstr[i] != '\0'; i++) {
		s.data[i] = cstr[i];
	}
	s.length = i;
}

void DestroyStr(SqString &s) {

}

void show(SqString s) {
	int i;
	if (s.length > 0) {
		for (i = 0; i < s.length; i++) {
			cout << s.data[i];
		}
		cout << endl;
	}
}
SqString jiami(SqString p) {
	int i = 0, j = 0;
	SqString q;		//接收加密对应的字符
	for (i = 0; i <= p.length; i++) {
		j = 0;
		while (p.data[i] != sqStr.data[j] && j < sqStr.length) {
			j++;	//用j控制对应映射位置的字符
		}
		if (j >= sqStr.length)
			q.data[i] = p.data[i];
		else
			q.data[i] = matchStr.data[j];	//将映射的字符赋给字符串q的数据
	}
	q.length = p.length;
	return q;
}
SqString jiemi(SqString q) {
	int i = 0, j;
	SqString p;		//接收解密对应的字符
	for (i = 0; i <= q.length; i++) {
		j = 0;
		while (q.data[i] != matchStr.data[j] && j < matchStr.length) {
			j++;	//用j控制对应解密位置的字符
		}
		if (j >= matchStr.length)
			p.data[i] = q.data[i];
		else
			p.data[i] = sqStr.data[j];		//将解密的字符赋给字符串q的数据
	}
	p.length = q.length;
	return p;
}
int main() {
	SqString jiami(SqString p);			//函数声明
	SqString jiemi(SqString q);			//函数声明
	SqString p, q;
	char inputStr[MaxSize];					//存放输入的字符串
	char sqChar[MaxSize] = "abcdefghijklmnopqrstuvwxyz";		//顺序字符串
	char matchChar[MaxSize] = "ngzqtcobmuhelkpdawxfyivrsj";		//映射字符串
	create(sqStr, sqChar);
	create(matchStr, matchChar);
	cout << "输入字符串：" << endl;
	cin >> inputStr;
	create(p, inputStr);
	cout << "原文串:" << endl;
	show(p);
	q = jiami(p);
	cout << "加密串:" << endl;
	show(q);
	p = jiemi(q);
	cout << "解密串:" << endl;
	show(p);

	system("pause");
	return 0;
}

实验要求

1.1 实验目的

掌握串的应用算法设计。

1.2实验内容

一个文本串可用事先给定的字母映射表进行加密。例如，设字母映射表为：

a b c d e f g h i j k l m n o p q r s t u v w x y z

n g z q t c o b m u h e l k p d a w x f y I v r s j

则字符串“encrypt”被加密为“tkzwsdf”。编写一个程序exp4-4.cpp,将输入的文本串加密后输出，然后进行解密并输出。