$文本串加密和解密程序

#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;
}