Need in c++ please explain your code

#include

#include

#include

//only from A-Z

using namespace std;

// get the ciphered text

string encryption(string strng, int);

// decrypt the cipher text

string decryption(string strng, int);

int main(int argc, char* argv[])

{

if(argc != 3)

{

cout

return 1;

}

bool encryptFlag = false;

//check whethere we have to encrypt or decrypt

if(strcmp(argv[1], "-e") == 0)

encryptFlag = true;

else

encryptFlag = false;

//get the no. of shift

int n = atoi(argv[2]);

string line;

string converted;

while(getline(cin, line))

{

if(encryptFlag)

converted = encryption(line, n);

else

converted = decryption(line, n);

cout

}

return 0;

}

// get the ciphered text

string encrypt(string strng, int n)

{

int i;

for( i = 0 ; i

{

// to get ascii convert string to int

int ascii = (int)strng[i];

if(ascii >= 'A' && ascii

{

ascii = ascii + n;

if(ascii

ascii = 91 - ( 65 - ascii );

else if(ascii > 90)

ascii = 64 + (ascii - 90);

// update the character with the ciphered text

strng[i] = (char)ascii;

}

}

return strng;

}

// decrypt the cipher text

string decryption(string strng, int n)

{

int i;

for( i = 0 ; i

{

// get the ascii code

int ascii = (int)strng[i];

if(ascii >= 'A' && ascii

{

ascii = ascii - n;

if(ascii

ascii = 91 - ( 65 - ascii );

else if(ascii > 90)

ascii = 64 + (ascii - 90);

// update the character with the ciphered text

strng[i] = (char)ascii;

}

}

return strng;

}

Task 4 (Weightage 25%) Thus far the program only handles capital letters A-Z Now add support for small letters a-z and digits 0-9 Assume that for letters shift values are between-26 and +26 and for digits shift values are between 10 and +10. This program will support both input and output files and io redirection Usage Say file in.txt contains Good dos 2 Then the following command create an output file as seen below $ ./caesar -- 1 3 in.txt output.txt Contents of output.txt file Hppe eph 5 Similarly, we can decrypt output.txt to create original.txt as follows $ ./caesar -d 1 3 in.txt original.txt The contents of the original.txt are Good dog 2