ch2-The Basics

Chapter_2 

Contents:

Scope.cpp     ch2-Types     Init.cpp     Ref.cpp     

Scope.cpp     CS, p. 7

#include <iostream>

using std::cout;

using std::endl;

int a = 0; // global a

int main()

{

  cout << "a = " << a << endl; // global `a'

  cout << "::a = " << ::a << endl; // global `a'

  int a = 1; // hides global `a'

  cout << "a = " << a << endl; // local `a' (main)

  cout << "::a = " << ::a << endl; // global `a'

  { // inner scope

    int a = 2; // hides global `a' and `a' from main()

    cout << "a = " << a << endl; // local `a' (inner scope)

    cout << "::a = " << ::a << endl; // global `a'

  }

  cout << "a = " << a << endl; // local `a' (main)

  cout << "::a = " << ::a << endl; // global `a'

  return 0;

}

/*

g++ Scope.cpp -o Scope

./Scope

a = 0

::a = 0

a = 1

::a = 0

a = 2

::a = 0

a = 1

::a = 0

*/

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ch2-Types     CS, p. 7-8

types.c

#include <stdio.h> // for printf()

#include <stdbool.h> // for bool, false, true

// /usr/lib/gcc/x86_64-linux-gnu/9/include/stdbool.h

int main()

{

  char c = false; // no error, no warning

  bool b = false;

  // b = 0; // no error, no warning

  printf("(int) c = %d\n", (int) c); // 0

  printf("(bool) b = %d\n", (bool) b); // 0

  // b--; // compile error

  c++;

  b++; // no warning

  // c = true; // no error, no warning

  printf("(int) c = %d\n", (int) c); // 1

  printf("(bool) b = %d\n", (bool) b); // 1

  c++;

  b++; // no warning

  // b = -10; // no error, no warning, but `b' remains 1

  // b = 10; // no error, no warning, but `b' remains 1

  // c = true + 10; // c == 11

  printf("(int) c = %d\n", (int) c); // 2

  printf("(bool) b = %d\n", (bool) b); // 1

  b = 10; // b == 1

  printf("(bool) c = %d\n", (bool) c); // 1

  printf("(int) b = %d\n", (int) b); // 1

  c = 65, b = 0;

  printf("c = '%c'\n", c); // 'A' (ASCII 65)

  printf("(int) c = %d\n", (int) c); // 65

  printf("(bool) c = %d\n", (bool) c); // 1

  printf("(int) b = %d\n", (int) b); // 0

  printf("(bool) b = %d\n", (bool) b); // 0

  return 0;

}

/*

gcc types.c -o types

./types

(int) c = 0

(bool) b = 0

(int) c = 1

(bool) b = 1

(int) c = 2

(bool) b = 1

(bool) c = 1

(int) b = 1

c = 'A'

(int) c = 65

(bool) c = 1

(int) b = 0

(bool) b = 0

*/

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Types.cpp

#include <iostream>

using std::cout;

using std::endl;

int main()

{

  char c = false; // no error, no warning

  bool b = false;

  // b = 0; // no error, no warning

  cout << "(int) c = " << (int) c << endl; // 0

  cout << "(bool) b = " << (bool) b << endl; // 0

  // b--; // compile error

  c++;

  b++; // warning: deprecated

  // c = true; // no error, no warning

  cout << "(int) c = " << (int) c << endl; // 1

  cout << "(bool) b = " << (bool) b << endl; // 1

  c++;

  b++; // warning: deprecated

  // b = -10; // no error, no warning, but `b' remains 1

  // b = 10; // no error, no warning, but `b' remains 1

  // c = true + 10; // c == 11

  cout << "(int) c = " << (int) c << endl; // 2

  cout << "(bool) b = " << (bool) b << endl; // 1

  b = 10; // b == 1

  cout << "(bool) c = " << (bool) c << endl; // 1

  cout << "(int) b = " << (int) b << endl; // 1

  c = 65, b = 0;

  cout << "c = " << '\'' << c << "\'" << endl; // 'A' (ASCII 65)

  cout << "(int) c = " << (int) c << endl; // 65

  cout << "(bool) c = " << (bool) c << endl; // 1

  cout << "(int) b = " << (int) b << endl; // 0

  cout << "(bool) b = " << (bool) b << endl; // 0

  return 0;

}

/*

g++ Types.cpp -o Types

Types.cpp: In function ‘int main()’:

Types.cpp:14:4: warning: use of an operand of type ‘bool’ in

‘operator++’ is deprecated [-Wdeprecated]

   14 |   b++; // warning: deprecated

      |    ^~

Types.cpp:20:4: warning: use of an operand of type ‘bool’ in

‘operator++’ is deprecated [-Wdeprecated]

   20 |   b++; // warning: deprecated

      |    ^~

./Types

(int) c = 0

(bool) b = 0

(int) c = 1

(bool) b = 1

(int) c = 2

(bool) b = 1

(bool) c = 1

(int) b = 1

c = 'A'

(int) c = 65

(bool) c = 1

(int) b = 0

(bool) b = 0

*/

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Init.cpp     CS, p. 9; CPL, p. 41

#include <iostream>

using std::cout;

using std::endl;

int main() // initializations

{

  int a = 0;

  int b(1);

  int c{2};

  cout << "a = " << a << ", b = " << b << ", c = " << c << endl;

  return 0;

}

/*

g++ Init.cpp -o Init

./Init

a = 0, b = 1, c = 2

*/

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Ref.cpp     CS, p. 11

#include <iostream>

using std::cout;

using std::endl;

int main() // references and pointers

{

  int i = 0;

  int &ri = i;

  int *pi = &i;

  cout << "i = " << i << ", ri = " << ri << ", *pi = " << *pi << endl;

  i++;

  cout << "i = " << i << ", ri = " << ri << ", *pi = " << *pi << endl;

  ri++;

  cout << "i = " << i << ", ri = " << ri << ", *pi = " << *pi << endl;

  (*pi)++;

  cout << "i = " << i << ", ri = " << ri << ", *pi = " << *pi << endl;

  return 0;

}

/*

g++ Ref.cpp -o Ref

./Ref

i = 0, ri = 0, *pi = 0

i = 1, ri = 1, *pi = 1

i = 2, ri = 2, *pi = 2

i = 3, ri = 3, *pi = 3

*/

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