458 - The Decoder

Write a complete program that will correctly decode a set of characters into a valid message. Your program should read a given file of a simple coded set of characters and print the exact message that the characters contain. The code key for this simple coding is a one for one character substitution based upon a single arithmetic manipulation of the printable portion of the ASCII character set.

Input and Output

For example: with the input file that contains:

1JKJ'pz'{ol'{yhklthyr'vm'{ol'Jvu{yvs'Kh{h'Jvywvyh{pvu5
1PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu5
1KLJ'pz'{ol'{yhklthyr'vm'{ol'Kpnp{hs'Lx|pwtlu{'Jvywvyh{pvu5

your program should print the message:

*CDC is the trademark of the Control Data Corporation.
*IBM is a trademark of the International Business Machine Corporation.
*DEC is the trademark of the Digital Equipment Corporation.

Your program should accept all sets of characters that use the same encoding scheme and should print the actual message of each set of characters.

在密码学里面有一种很简单的加密方式，就是把明码的每个字元加上某一个整数K而得到密码的字元（明码及密码字元一定都在ASCII码中可列印的范围内）。例如若K=2，那么apple经过加密后就变成crrng了。解密则是反过来做。这个问题是给你一个密码字串，请你依照上述的解密方式输出明码。

Input

每笔测试资料一列。每列有1个字串，就是需要解密的明码。

Output

对每一测试资料，请输出解密后的密码。

Sample Input

1JKJ'pz'{ol'{yhklthyr'vm'{ol'Jvu{yvs'Kh{h'Jvywvyh{pvu5
1PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu5
1KLJ'pz'{ol'{yhklthyr'vm'{ol'Kpnp{hs'Lx|pwtlu{'Jvywvyh{pvu5

Sample Output

*CDC is the trademark of the Control Data Corporation.
*IBM is a trademark of the International Business Machine Corporation.
*DEC is the trademark of the Digital Equipment Corporation.
解题思路：找出先k值，然后用getchar输入，注意'\n'

#include <stdio.h>   
int main()  
{  
    char c;  
    while ((c = getchar()) != EOF)  
        if (c != '\n')  
            putchar(c - 7);  
        else   
            printf("\n");  
    return 0;  
}