How do I increment letters in c++?

Question

I'm creating a Caesar Cipher in c++ and i can't figure out how to increment a letter.

I need to increment the letter by 1 each time and return the next letter in the alphabet. Something like the following to add 1 to 'a' and return 'b' .

char letter[] = "a";
cout << letter[0] +1;

Answer 1

This snippet should get you started. letter is a char and not an array of char s nor a string.

The static_cast ensures the result of 'a' + 1 is treated as a char .

> cat caesar.cpp          
#include <iostream>

int main()
{
    char letter = 'a';
    std::cout << static_cast<char>(letter + 1) << std::endl;
}

> g++ caesar.cpp -o caesar
> ./caesar                
b

Watch out when you get to 'z' (or 'Z' !) and good luck!

Answer 2

It works as-is, but because the addition promotes the expression to int you want to cast it back to char again so that your IOStream renders it as a character rather than a number:

int main() {
   char letter[] = "a";
   cout << static_cast<char>(letter[0] + 1);
}

Output : b

Also add wrap-around logic (so that when letter[0] is z , you set to a rather than incrementing), and consider case.

Answer 3

Does letter++ work? All in all char is a numeric type, so it will increment the ascii code . But I believe it must be defined as char letter not an array. But beware of adding one to 'Z'. You will get '[' =P

#include <iostream>

int main () {
    char a = 'a';
    a++;
    std::cout << a;
}

This seems to work well ;)

Answer 4

waleed@waleed-P17SM-A:~$ nano Good_morning_encryption.cpp waleed@waleed-P17SM-A:~$ g++ Good_morning_encryption.cpp -o Good_morning_encryption.out waleed@waleed-P17SM-A:~$ ./Good_morning_encryption.out Enter your text:waleed Encrypted text: jnyrrq waleed@waleed-P17SM-A:~$ cat Good_morning_encryption.cpp

    #include <iostream>
    #include <string>

    using namespace std;


    int main() {

    //the string that holds the user input
    string text;
    //x for the first counter than makes it keeps looping until it encrypts the user input
    //len holds the value (int) of the length of the user input ( including spaces)
    int x, len;

    //simple console output
    cout << "Enter your text:";
    //gets the user input ( including spaces and saves it to the variable text
    getline(cin, text);
    //give the variable len the value of the user input length
    len = (int)text.length();
    //counter that makes it keep looping until it "encrypts" all of the user input (that's why it keeps looping while its less than len
    for(x = 0; x < len; x++) {
    //checks each letts (and spaces) in the user input (x is the number of the offset keep in mind that it starts from 0 and for example text[x] if the user input was waleed would be w since its text[0]
    if (isalpha(text[x])) {
    //converts each letter to small letter ( even though it can be done another way by making the check like this if (text[x] =='z' || text[x] == 'Z')
    text[x] = tolower(text[x]);
    //another counter that loops 13 times
    for (int counter = 0; counter < 13; counter++) {

    //it checks if the letts text[x] is z and if it is it will make it a
    if (text[x] == 'z') {

    text[x] = 'a';

    } 
    //if its not z it will keeps increamenting (using the loop 13 times)
    else {


    text[x]++;

    }

    }
    }
    }
//prints out the final value of text
    cout << "Encrypted text:\n" << text << endl;
    //return 0 (because the the main function is an int so it must return an integer value
    return 0;

    }

Note: this is called caeser cipher encryption it works like this :

ABCDEFGHIJKLMNOPQRSTUVWXYZ NOPQRSTUVWXYZABCDEFGHIJKLM so for example my name is waleed it will be written as : JNYRRQ so its simply add 13 letters to each letter

i hope that helped you

Answer 5

You can use 'a'+((letter - 'a'+n)%26); assuming after 'z' you need 'a' ie 'z'+1='a'

    #include <iostream>

    using namespace std;

    int main()
    {
       char letter='z';
       cout<<(char)('a' + ((letter - 'a' + 1) % 26));

       return 0;
    }

See this https://stackoverflow.com/a/6171969/8511215

Answer 6

char letter = 'a'; 
cout << ++letter;

Answer 7

它有效，但不要忘记，如果你增加“z”，你需要得到“a”，所以也许你应该通过一个检查函数，当你得到“z”时输出“a”。

Answer 8

将 letter[n] 转换为 byte* 并将其引用值增加 1。