// ============================================
// C Strings (p. 4)

int main()
{
  char c = '0';
  cout << static_cast<int>(c) << " ";
  c = 'A';
  cout << static_cast<int>(c) << " ";
  c = '\n';
  cout << static_cast<int>(c) << " ";
  return 0;
}

int main()
{
  char c = 48;
  cout << c << " ";
  c += 10;
  cout << c << " ";
  if(c > 50)
    cout << c << " ";
  return 0;
}





// ============================================
// C Strings (p. 5)

int main()
{
  int a = 0, b = 0;
  char c = 0;

  do
  {
    cout << "Enter two integers: ";
    cin >> a >> b;
    cout << "Add? ";
    cin >> c;
  } while(c != 'Y' && c != 'y');
  cout << a + b << "\n";

  return 0;
}





// ============================================
// C Strings (p. 6)

#include <iostream>
using namespace std;

int main()
{
  char c = 0;
  while(cin >> c)
  {
    if(65 <= c && c <= 90)
      cout << static_cast<char>(c + 32);
    else
      cout << c;
    cout << "\n";
  }
  return 0;
}





// ============================================
// C Strings (p. 8)

#include <iostream>
#include <cctype>
using namespace std;

int main()
{
  char c = 0;
  while(cin >> c)
    cout << static_cast<char>(tolower(c)) << "\n";
  return 0;
}







// ============================================
// C Strings (p. 10)

#include <iostream>
#include <iomanip>
#include <cctype>
using namespace std;

int main()
{
  cout << "   0123456789\n";
  for(int i = 30; i <= 126; i++) 
  {
    if(i % 10 == 0)
      cout << setw(2) << i / 10 << " ";
    if(isprint(i))
      cout << static_cast<char>(i);
    else
      cout << " ";
    if(i % 10 == 9)
      cout << "\n";
  }  
  return 0;
}




// ============================================
// C Strings (p. 14)

#include <iostream>
using namespace std;

const int LEN = 10;
int main()
{
  char s[LEN] = {0};
  int n = 0;
  do
  {
    cin >> s[n];
    n++;
  } while(s[n - 1] != '#' && n < LEN);
  for(int i = 0; i < n - 1; i++)
    cout << s[i];
  return 0;
}





// ============================================
// C Strings (p. 15)

char str[10]; 
cin >> str; // if we type "abcde"
cout << str[0]; // a
cout << str[2]; // c





// ============================================
// C Strings (p. 16)

int values[5] = {0};
cout << values; // an address
char str[10]; 
cin >> str; // if we type "abcde"
cout << str; // abcde





// ============================================
// C Strings (p. 18)

char a[100] = "abcde FGH";
cout << a << "\n"; // abcde FGH
char b[100] = "abcde\0 FGH";
cout << b << "\n"; // abcde





// ============================================
// C Strings (p. 20)

#include <iostream>
using namespace std;

const int LEN = 10;
int main()
{
  char s[LEN] = {0};
  cin >> s;
  cout << s << "\n";
  return 0;
}





// ============================================
// C Strings (p. 22)

char c[100] = {0};
cin >> c; // "123456789"
cin >> c; // "abcde";
cout << c << "\n"; // "abcde"
c[5] = '*';
cout << c << "\n"; // "abcde*789"





// ============================================
// C Strings (p. 24)

char a1[100] = {0};
cin >> a1; // "this is a string"
cout << a1; // "this"

char a2[100] = {'a', 'b', ' ', 'c', '\0', 'e'};
cout << a2; // ab c





// ============================================
// C Strings (p. 25)

char a[100] = {0};
char b[100] = {0};
cin >> a >> b; // this is
cout << a << "\n"; // this
cout << b << "\n"; // is

char a[100];
cin.getline(a, 100); // Hi, it's me
cout << a << "\n"; // Hi, it's me





// ============================================
// C Strings (p. 26)

char a[100] = {0};
while(cin.getline(a, 100))
{
  int i = 0;
  int spaceCount = 0;

  while(a[i] != '\0')
  {
    if(a[i] == ' ')
      spaceCount++;
    i++;
  }
  cout << spaceCount << "\n";
}





// ============================================
// C Strings (p. 27)

char name[4][10] = {"John", "Mikasa", "Eren", "Armin"};
cout << name << "\n"; // an address
cout << name[1] << "\n";
cin >> name[2];
cout << name[2][0] << "\n";





// ============================================
// C Strings (p. 28)

char s[100] = "12345";
char* p = s;
cout << p << "\n"; 
cin >> p; // or s
cout << s; // or p

char s[100] = "12345";
char* p = s;
cout << p + 2 << "\n"; 





// ============================================
// C Strings (p. 30)

char* p = "12345";
cout << p + 2 << "\n"; // 345






// ============================================
// C Strings (p. 33)

#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
  for(int i = 0; i < argc; i++)
    cout << argv[i] << "\n";
  return 0;
}





// ============================================
// C Strings (p. 38)

char* p = new char[100];
cin >> p;
cout << strlen(p);
p[3] = '\0';
cout << strlen(p + 1);
delete [] p;

char* p = "12345";
cout << strlen(p) << "\n";
char a[100] = "1234567";
cout << strlen(a) << "\n";





// ============================================
// C Strings (p. 39)

char* p = "12345";
cout << strlen(p) << "\n";
char a[100] = "1234567890";
cout << strlen(a) << "\n";
cout << sizeof(a) << "\n";
cout << sizeof(a + 2) << "\n";





// ============================================
// C Strings (p. 41)

char a[100] = "1234567890";
char* p = strchr(a, '8');
if(strchr(a, 'a') == nullptr)
  cout << "!!!\n";
cout << strchr(a, '4') << "\n";
cout << strchr(a, '4') - a;





// ============================================
// C Strings (p. 42)

char a[100] = "this is a book";
char* p = strchr(a, ' ');
while(p != nullptr)
{
  *p = '_';
  p = strchr(p, ' '); // why p?
}
cout << a;





// ============================================
// C Strings (p. 48)

char a[100] = "this is a book";
char* p = strstr(a, "is");
while(p != nullptr)
{
  *p = 'I'; // not p = "IS"!
  *(p + 1) = 'S';  
  p = strstr(p, "is");
}
cout << a;




// ============================================
// C Strings (p. 56)

char a[100] = "1234";
cout << atoi(a) * 2 << "\n";
char b[100] = "-12.34";
cout << atof(b) / 2 << "\n";

char a[100] = {0};
itoa(123, a, 2);
cout << a << "\n";
itoa(123, a, 10);
cout << a[2] << " " << a << "\n";




// ============================================
// C Strings (p. 57)

char a[100] = "the";
char b[100] = "they";
char c[100] = "them";
cout << strcmp(a, b) << "\n";
cout << strcmp(b, c) << " " << strncmp(b, c, 2);




// ============================================
// C Strings (p. 58)

char a[100] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcpy(a, b);
cout << a << "\n";

char a[100] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcpy(a, b);
cout << a + 7 << "\n"; // ?




// ============================================
// C Strings (p. 57)

char a[100] = "the";
char b[100] = "they";
char c[100] = "them";
cout << strcmp(a, b) << "\n";
cout << strcmp(b, c) << " " << strncmp(b, c, 2);




// ============================================
// C Strings (p. 58)

char a[100] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcpy(a, b);
cout << a << "\n";

char a[100] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcpy(a, b);
cout << a + 7 << "\n"; // ?




// ============================================
// C Strings (p. 60)

char a[100] = "this is a book";
char* p = strstr(a, "is");
while(p != nullptr)
{
  strcpy(p, "IS");
  p = strstr(p, "is");
}
cout << a;




// ============================================
// C Strings (p. 63)

char a[100] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcat(a, b);
cout << a << "\n";




// ============================================
// C Strings (p. 65)

char a[15] = "watermelon";
char b[100] = "orange";
cout << a << "\n";
strcat(a, b); // dangerous!
cout << a << "\n";

char* a;
char b[100] = "orange";
strcat(a, b); // dangerous!





// ============================================
// C Strings (p. 66)

char a[15] = "watermelon";
char b[100] = "orange";
strncat(a, b, sizeof(a) - strlen(a) - 1);
cout << a << "\n";




// ============================================
// C Strings (p. 68)

#include <iostream>
#include <cstring>
using namespace std;

const int CNT = 4;
const int LEN = 10;

void swapName(char* n1, char* n2)
{
  char temp[LEN] = {0};
  strcpy(temp, n1);
  strcpy(n1, n2);
  strcpy(n2, temp);
}

int main()
{
  char name[CNT][LEN] 
    = {"John", "Mikasa", "Eren", "Armin"};

  for(int i = 0; i < CNT; i++)
    for(int j = 0; j < CNT - i - 1; j++)
      if(strcmp(name[j], name[j + 1]) > 0)
        swapName(name[j], name[j + 1]);

  for(int i = 0; i < CNT; i++)
    cout << name[i] << " ";
    
  return 0;
}





// ============================================
// C Strings (p. 85)

#include <iostream>
#include <cstring>
using namespace std;

const int CNT = 4;
const int LEN = 10;

void swapPtr(char*& p1, char*& p2)
{
  char* temp = p1;
  p1 = p2;
  p2 = temp;
}

int main()
{
  char name[CNT][LEN] 
    = {"John", "Mikasa", "Eren", "Armin"};
  char* ptr[CNT] 
    = {name[0], name[1], name[2], name[3]};
  
  for(int i = 0; i < CNT; i++)
    for(int j = 0; j < CNT - i - 1; j++)
      if(strcmp(ptr[j], ptr[j + 1]) > 0)
        swapPtr(ptr[j], ptr[j + 1]);
        
  for(int i = 0; i < CNT; i++)
    cout << ptr[i] << " ";
    
  return 0;
}




// ============================================
// C Strings (p. 102)

#include <iostream>
#include <cstring>
using namespace std;

const int CNT = 100;
const int WORD_LEN = 50;
const int SEN_LEN = 1000;

int main()
{
  char url[SEN_LEN];
  char delim[] = ".\\";
  char word[CNT][WORD_LEN] = {0};
  int wordCnt = 0;

  cin >> url;
  char* start = strtok(url, delim);
  while(start != nullptr)
  {
    strcpy(word[wordCnt], start);
    wordCnt++;
    start = strtok(nullptr, delim);
  }
  
  for(int i = 0; i < wordCnt; i++)
    cout << word[i] << " ";

  return 0;
}