Mapping an numeric value or symbol to a letter is called developing a character set. The ASCII character set referenced by the previous posts is one of the standard character sets available, but you can create your own. This is one step in the process of encryption, because you translate a known value to one that makes sense only if you know the conversion/translation. if/else statements, switch statement, and maps are relatively simple mechanisms to accomplish this.
if(num == 1)
cout << 'a';
else if (num == 3791)
cout << 'b';
else if (num = -53.21)
cout << 'c';
.
.
.
else if(num == 5e367)
cout << 'z';
The translation/conversion can be whatever you want.
