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  1. #include <stdio.h>
  2.  
  3. int isalphabet(char c){
  4. 	return(("A"<=c&&c<="Z")||("a"<=c&&c<="z"));
  5. }
  6.  
  7. char caesar(char c, int n){
  8. 	if(!isalphabet(c)) return c;
  9. 	int base = ("A"<=c&&c<="Z")?"A":"a";
  10. 	int pos = c-base;
  11. 	int shifted = (pos + n)%26;
  12. 	if(shifted<0)shifted+= 26;
  13. 	return base + shifted;
  14. }
  15.  
  16. void encrypt(char str[],int n){
  17. 	int i = 0;
  18. 	while(str[i]){
  19. 		str[i] = caesar(str[i],n);
  20. 		i++;
  21. 	}
  22. }
  23.  
  24. int main(void){
  25. 	char text[128];
  26. 	int shift;
  27.  
  28. 	printf("文字列を入力せよ:\n");
  29. 	scanf("%s",text);
  30.  
  31. 	printf("シフト数を入力せよ(正の数):\n");
  32. 	scanf("%d",&shift);
  33.  
  34. 	encrypt(text, shift);
  35. 	printf("暗号化:%s\n",text);
  36.  
  37. 	encrypt(text,-shift);
  38. 	printf("暗号化:%s\n",text);
  39.  
  40. 	return 0;
  41. }
Success #stdin #stdout 0s 5328KB
comments (?)
stdin
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hello
stdout
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文字列を入力せよ:
シフト数を入力せよ(正の数):
暗号化:hello
暗号化:hello
https://ideone.com/8ahtnT
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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