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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <stdlib.h>
  4. #include <assert.h>
  5.  
  6. char *verschluesseln(char *s, int n);
  7. char *entschluesseln(char *s, int n);
  8.  
  9. int main()
  10. {
  11. #define STR "DIESERKLARTEXTISTJETZTZUVERSCHLUESSELN"
  12.  
  13.   char str[] = STR;
  14.   char *ver;
  15.   char *ent;
  16.  
  17.   printf("unverschluesselt: %s\n", str);
  18.  
  19.   ver = verschluesseln(str, 3);
  20.   printf("verschluesselt:   %s\n", ver);
  21.  
  22.   ent = entschluesseln(ver, 3);
  23.   printf("entschluesselt:   %s\n", ent);
  24.  
  25.   assert(strcmp(ent, STR) == 0);
  26.  
  27.   return 0;
  28. }
  29.  
  30. char *verschluesseln(char *s, int n)
  31. {
  32.   int i, x = strlen(s) / n + ((strlen(s) % n) > 0);
  33.   char *b = malloc(strlen(s));
  34.   for (i = 0; s[i] != '\0'; i++)
  35.   {
  36.     b[x*(i%n) + i / n] = s[i];
  37.   }
  38.   for (i = 0; s[i] != '\0'; i++)
  39.   {
  40.     s[i] = b[i];
  41.   }
  42.   free(b);
  43.   return s;
  44. }
  45.  
  46. char *entschluesseln(char *s, int n)
  47. {
  48.   int i, x = strlen(s) / n + ((strlen(s) % n) > 0);
  49.   char *b = malloc(strlen(s));
  50.   for (i = 0; s[i] != '\0'; i++)
  51.   {
  52.     b[i] = s[x*(i%n) + i / n];
  53.   }
  54.   for (i = 0; s[i] != '\0'; i++)
  55.   {
  56.     s[i] = b[i];
  57.   }
  58.   free(b);
  59.   return s;
  60. }
  61.  
  62.  
Success #stdin #stdout 0s 2144KB
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stdin
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Standard input is empty
stdout
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unverschluesselt: DIESERKLARTEXTISTJETZTZUVERSCHLUESSELN
verschluesselt:   DSKRXSETVSLSLIELTTTTZECUSNERAEIJZURHEE
entschluesselt:   DIESERKLARTEXTISTJETZTZUVERSCHLUESSELN
https://ideone.com/F2OmhX
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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