How do I make the loop come true to me from every letter of the word?

Question

I have written this codefor (int i = 0 , n = strlen(alphabet); i < n ; i++), but only the first character has been verified. I think I need another loop, so I have written this code for (int j = 0 ; j <= i; j++) but it also not working. I want to encrypt the input text, so I want the loop to be verified from all the letter in the words. So this program encrypts just one letter. I think to the problem from the loop for (int i = 0 , n = strlen(alphabet); i < n ; i++)

#include

include

include

include

include

int main(int argc, string argv[]) { if (argc < 0 ){ printf("usage: ./caesar key"); return 1; }

int k = atoi (argv[1]);
 string alphabet = get_string("plaintext: ");
int c =0 , alph = 0 ;
for (int  i = 0 , n = strlen(alphabet); i < n ; i++)
 {
      alph = alphabet[i];
  //   for (int j = 0 ; j <= i; j++){
    if (isalpha (alph)){

        if (isupper (alph)){
            alph = alph -'A';
            c = (alph + k) % 26 ;
            alph = c + 'A' ;
        } else {
          alph = alphabet[i] - 'a' ;
            c = (alph + k) % 26 ;
           alph = c + 'a' ;
        }

    }

    printf("ciphertext: %c \n", alph);
   return 0;
    // }

 } }

Answer 1

The reason this loop for (int i = 0 , n = strlen(alphabet); i < n ; i++) only processes the first letter is because of the placement of return 0;. It is inside the loop, and "return"s from the main function, which ends the program. Program should not return until after the loop finishes executing.