UVa 458 The Decoder（解码器）

 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{pvu51PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu51KLJ'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.

Sample Input

1JKJ'pz'{ol'{yhklthyr'vm'{ol'Jvu{yvs'Kh{h'Jvywvyh{pvu51PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu51KLJ'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.

 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{pvu51PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu51KLJ'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.

Sample Input

1JKJ'pz'{ol'{yhklthyr'vm'{ol'Jvu{yvs'Kh{h'Jvywvyh{pvu51PIT'pz'h'{yhklthyr'vm'{ol'Pu{lyuh{pvuhs'I|zpulzz'Thjopul'Jvywvyh{pvu51KLJ'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.

解析：

题目比较简单，即使ASCII减7就可以了。但是要注意字符串的输入，可以用scanf函数，也可以用gets函数，但是使用getchar()，注意‘\n'时候不能进行翻译，应该直接换行。

1.使用scanf函数

#include <stdio.h>#include <stdlib.h>#include <string.h>char str[200];int main(){    int i;    while(~scanf("%s", str)){        for(i = 0; i<strlen(str); i++){            printf("%c", str[i]-7);        }        printf("\n");    }    return 0;}

2.使用gets函数

#include <stdio.h>#include <stdlib.h>#include <string.h>char str[200];int main(){    int i;    while(gets(str)){        for(i = 0; i<strlen(str); i++){            str[i] = str[i]-7;        }        puts(str);    }    return 0;}

3.使用getchar()

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