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  1. #include <stdio.h>
  2.  
  3. int isalphabet(char c) {
  4.     if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
  5.         return 1;
  6.     else
  7.         return 0;
  8. }
  9.  
  10. char caesar(char c, int n) {
  11.     if (!isalphabet(c))
  12.         return c;
  13.  
  14.     int base = (c >= 'A' && c <= 'Z') ? 'A' : 'a';
  15.     int pos = c - base;
  16.     pos = (pos + n) % 26;
  17.     if (pos < 0)
  18.         pos += 26;
  19.     return base + pos;
  20. }
  21.  
  22. int main() {
  23.     char input[256];
  24.     int n;
  25.     scanf("%d", &n);
  26.     scanf(" %[^\n]", input);
  27.  
  28.     for (int i = 0; input[i] != '\0'; i++) {
  29.         input[i] = caesar(input[i], n);
  30.     }
  31.     printf("Encrypted: %s\n", input);
  32.  
  33.     for (int i = 0; input[i] != '\0'; i++) {
  34.         input[i] = caesar(input[i], -n);
  35.     }
  36.     printf("Decrypted: %s\n", input);
  37.  
  38.     return 0;
  39. }
Success #stdin #stdout 0.01s 5328KB
comments (?)
stdin
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3 Hello,World!
stdout
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Encrypted: Khoor,Zruog!
Decrypted: Hello,World!
https://ideone.com/QQKHzs
language:
C (gcc 8.3)
created:
8 days ago
visibility:
public

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