程序代码：

#include "iostream"
#include "string"
//#include "fstream"
using namespace std;

int main(int argc, char* argv[])
{
    //ifstream cin("aaa.txt");
    char a[27] = "abcdefghijklmnopqrstuvwxyz";
    char b[26];
    char c[100];
    while (cin.getline(b,27))
    {
        cin.getline(c,80);
        char d[26],e[26];
        for (int t = 0 ; t < 26 ; ++t )
        {
            d[t] = b[t] - 32 ;
            e[t] = a[t] - 32 ;
        }
        for (int i = 0 ; i < strlen(c) ; ++i )
        {
            if (c[i] == ' ')
            {
                cout<<" ";
                ++i ;
            }
            for (int j = 0 ; j < 26 ; ++j )
            {
                if (c[i] == a[j])
                {
                    cout<<b[j];
                    j = 27 ;
                }
                if (c[i] == e[j])
                {           
                    cout<<d[j];
                    j = 27 ;
                }
            }
        }
        printf("\n");
    }
    return 0;
}

程序代码：

#include<stdio.h>
#include<string.h>
int main()
{
    char key[28];
    char code[80];
    int i,j,len;
    while(NULL != gets(key))
    {
        gets(code);
        len = strlen(code);
        for(i = 0;i<len;i++)
        {
            if(code[i] != ' ')
            {
                if(code[i] >= 'a' && code[i] <= 'z')
                    code[i] = key[code[i]-97];
                else
                    code[i] = key[code[i]-65]-32;
            }
        }
        puts(code);
    }
    return 0;
}