In C++

Rotation cypher.

Characters are represented internally in C++ by the standard integer ASCII code.

Example:

s="Hello!";

v= 7210110810811133// ASCII code of string s

The 72 corresponds to "H," 101 to "e," etc. Here we will use the 94 codes for printable ASCII characters from 32 (space) up to 125 ("]") to make a rotation cipher. Think of the numbers from 32 to 125 on a circle:

[...32, 33, 34,... , 124, 125, 32, 33,...]

The cipher consists of replacing each character with ASCII code N with the character corresponding to the code 47 steps to the right around the circle. Code a function so=rot47(si)that returns the input string encrypted in this way. Using the function again should decrypt the string.

s=rot47(' Abort mission ')// encode Abort mission and return a string s

s= p3@CEO>:DD:@?] // encoded cyphertext

s= rot47(s)

s = Abort mission.// decoded cyphertext

Hint:

Convert the string into array of ASCII codes, add 47, if the result> 125 then subtract 94. First, generate the encoded text using rot47 function, then use the same function to decode the text back.