C++ need help finishing

Polybius was an ancient Greek writer who first proposed a method of substituting different two-digit numbers for each letter. The alphabet is written inside a 5-by-5 square matrix which has numbered rows and columns:

	1	2	3	4	5
1	A	B	C	D	E
2	F	G	H	I	J
3	K	L	M	N	O
4	P	Q	R	S	T
5	U	V	W	X	Y/Z

Note that Y andZ are written in the last cell to divde the letters evenly. The context o the message should make clear which of the two letters is intended.

To encode, substitute for each letter the numbers marking the row and column in which the letter appears. Always put the row number first. The word WATERMELON is encoded in a string as:

53114515433315323534

To decode, simply locate each letter indicated by the number. The first number, 53, tells you to find the letter at the intersection of the fifth row and the third column.

Riddle:

If you stand so that you face east and your back is to the west, what is on your left hand?

Answer:

21243422154344

Write functions that use the Polybius cypher to encode and decode strings. In particular, decode the answer to the riddle.

#include

#include

using namespace std;

const int gsize = 5;

string encode(const string& plain);

string decode(const string& cipher);

bool search2d(char a2d[][gsize], char target, int &row, int &col);

int main()

{

string cipher1 = encode("SILENCE");

string cipher2 = encode("DAYS");

string cipher3 = encode("DAZE");

cout << cipher1 << endl;

cout << cipher2 << endl;

cout << cipher3 << endl;

decode(cipher1);

decode(cipher2);

decode(cipher3);

system("pause");

return 0;

}

string encode(const string& plain)

{

static char grid[][gsize]{

{'A', 'B', 'C', 'D', 'E'},

{'F', 'G', 'H', 'I', 'J'},

{'K', 'L', 'M', 'N', 'O'},

{'P', 'Q', 'R', 'S', 'T'},

{'U', 'V', 'W', 'X', 'Y'}

};

string cipher = "";

int row, col;

for (int pos = 0; pos < plain.length(); pos++)

{

if (search2d(grid, plain[pos], row, col))

cipher = cipher + to_string(row + 1) + to_string(col + 1);

else if (plain[pos] == 'Z')

cipher = cipher + to_string(5) + to_string(5);

else

cipher = cipher + " ";

}

return cipher;

}

string decode(const string& cipher)

{

static char grid[][gsize]{

{'A', 'B', 'C', 'D', 'E'},

{'F', 'G', 'H', 'I', 'J'},

{'K', 'L', 'M', 'N', 'O'},

{'P', 'Q', 'R', 'S', 'T'},

{'U', 'V', 'W', 'X', 'Y'}

};

for (int pos = 0; pos < cipher.length(); pos += 2)

{

int row = stoi(string(1, cipher[pos]));

int col = stoi(string(1, cipher[pos + 1]));

cout << row << col << ' ';

}

cout << endl;

return "";

}

bool search2d(char a2d[][gsize],

char target, int &row, int &col)

{

for (row = 0; row < gsize; row++)

for (col = 0; col < gsize; col++)

if (a2d[row][col] == target)

return true;

return false;

}