Created
November 2, 2011 13:41
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| #include <stdio.h> | |
| #include <string.h> | |
| #define MAXSTR 50 | |
| char pt[MAXSTR], ct[MAXSTR], dt[MAXSTR] ; | |
| int i = 0; | |
| int trans(void){ /*Transposition Cypher | |
| *Swaps adjacent pairs of letters | |
| */ | |
| while (pt[i] != '\0' && pt[i+1] != '\0') /* while the 2 characters are not line terminators */ | |
| { | |
| ct[i] = pt [i+1]; /*swap the 2 characters*/ | |
| ct[i+1] = pt [i]; | |
| i = i+2; /*move on to next 2 characters*/ | |
| } | |
| if (pt[i] == '\0') /*even number of characters*/ | |
| { | |
| ct[i] = pt[i]; /*copy over line terminator*/ | |
| } | |
| else | |
| { | |
| ct[i] = pt[i]; /*copy over last character*/ | |
| ct[i+1] = pt[i+1]; /*copy over line terminator*/ | |
| } | |
| printf("encyphered text:\n%s\n", ct); | |
| return 0; | |
| } | |
| int rot13(void){ | |
| while (pt[i] != '\0') | |
| { | |
| switch (pt[i]){ | |
| case 'A' : ct[i] = 'N'; break; | |
| case 'B' : ct[i] = 'O'; break; | |
| case 'C' : ct[i] = 'P'; break; | |
| case 'D' : ct[i] = 'Q'; break; | |
| case 'E' : ct[i] = 'R'; break; | |
| case 'F' : ct[i] = 'S'; break; | |
| case 'G' : ct[i] = 'T'; break; | |
| case 'H' : ct[i] = 'U'; break; | |
| case 'I' : ct[i] = 'V'; break; | |
| case 'J' : ct[i] = 'W'; break; | |
| case 'K' : ct[i] = 'X'; break; | |
| case 'L' : ct[i] = 'Y'; break; | |
| case 'M' : ct[i] = 'Z'; break; | |
| case 'N' : ct[i] = 'A'; break; | |
| case 'O' : ct[i] = 'B'; break; | |
| case 'P' : ct[i] = 'C'; break; | |
| case 'Q' : ct[i] = 'D'; break; | |
| case 'R' : ct[i] = 'E'; break; | |
| case 'S' : ct[i] = 'F'; break; | |
| case 'T' : ct[i] = 'G'; break; | |
| case 'U' : ct[i] = 'H'; break; | |
| case 'V' : ct[i] = 'I'; break; | |
| case 'W' : ct[i] = 'J'; break; | |
| case 'X' : ct[i] = 'K'; break; | |
| case 'Y' : ct[i] = 'L'; break; | |
| case 'Z' : ct[i] = 'M'; break; | |
| case 'a' : ct[i] = 'n'; break; | |
| case 'b' : ct[i] = 'o'; break; | |
| case 'c' : ct[i] = 'p'; break; | |
| case 'd' : ct[i] = 'q'; break; | |
| case 'e' : ct[i] = 'r'; break; | |
| case 'f' : ct[i] = 's'; break; | |
| case 'g' : ct[i] = 't'; break; | |
| case 'h' : ct[i] = 'u'; break; | |
| case 'i' : ct[i] = 'v'; break; | |
| case 'j' : ct[i] = 'w'; break; | |
| case 'k' : ct[i] = 'x'; break; | |
| case 'l' : ct[i] = 'y'; break; | |
| case 'm' : ct[i] = 'z'; break; | |
| case 'n' : ct[i] = 'a'; break; | |
| case 'o' : ct[i] = 'b'; break; | |
| case 'p' : ct[i] = 'c'; break; | |
| case 'q' : ct[i] = 'd'; break; | |
| case 'r' : ct[i] = 'e'; break; | |
| case 's' : ct[i] = 'f'; break; | |
| case 't' : ct[i] = 'g'; break; | |
| case 'u' : ct[i] = 'h'; break; | |
| case 'v' : ct[i] = 'i'; break; | |
| case 'w' : ct[i] = 'j'; break; | |
| case 'x' : ct[i] = 'k'; break; | |
| case 'y' : ct[i] = 'l'; break; | |
| case 'z' : ct[i] = 'm'; break; | |
| default : ct[i] = pt[i]; | |
| } | |
| i = i + 1; | |
| } | |
| ct[i] = pt[i]; /*copy over the line terminator*/ | |
| printf("encyphered text:\n%s\n", ct); | |
| return 0; | |
| } | |
| int main(void){ | |
| int X; | |
| printf("enter a string less than 50 characters>"); | |
| scanf("%s", &pt); | |
| printf("0: Exit\n1: Transposition cypher\n2: ROT13\nEnter number > "); | |
| scanf("%d", &X); | |
| while (X != 0) | |
| { | |
| switch (X){ | |
| case 1 : trans(); break; | |
| case 2 : rot13(); break; | |
| } | |
| printf("0: Exit\n1: Transposition cypher\n2: ROT13\nEnter number > "); | |
| scanf("%d", &X); | |
| strncpy (pt, ct, MAXSTR); | |
| printf("%s\n%s\n", pt, ct); | |
| } | |
| return 0; | |
| } |
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