Cで作ったなんちゃってclojure関数たち

dolls.c

// 文字列版take
void take_char(int n, char* string, char* substring) {
  int i;

  for (i = 0; i < n; i++) {
    substring[i] = string[i];
  }

  substring[i+1] = '\0';
}

// 整数版reduce
int reduce_int(char operator,const int num[],const int count,const int result){

  switch (operator) {
    case '+':
      if (count == 0) {
        return result + num[count];
      } else {
        reduce_int('+',num,(count-1),(result + num[count]));
      }
      break;

    case '*':
      if (count == 0) {
        return result * num[count];
      } else {
        reduce_int('*',num,(count-1),(result * num[count]));
      }
      break;
  }
}

// 文字列版length
int length_char(char* str) {
  int i = 0;
  while (str[i] != '\0') {
    i++;
  }
  return (i+1);
}
  
// 文字列版drop
void drop_char(const int count, char* str) {
  int i = 0;

  while (str[i] != '\0') {
    str[i] = str[i+count];
    i++;
  }
}

使い方

char str[20];
take_char(5,"akameco",str);
print("%s\n",str); // akame

int fascination[3] = {100,200,400};
printf("%d\n",reduce_int('+',fascination,3,0)); // 700
printf("%d\n",reduce_int('*',fascination,3,0)); // 8000000