ch2-vector

Chapter_2     ch2-Files                                                                          ch2-Exercises 

Contents:

Intvector.cpp     Exercise_2-8     Exercise_2-9     Exercise_2-10

Intvector.cpp     TCP1, p. 117-118          download

// Creating a vector that holds integers

#include <iostream>

#include <vector>

using std::cout;

using std::endl;

using std::vector;

int main()

{

  vector<int> v;

  for(int i = 0; i < 10; i++)

  {v.push_back(i);}

  int size = v.size();

  for(int i = 0; i < size; i++)

  {cout << v[i] << ", ";}

  cout << endl;

  for(int i = 0; i < size; i++)

  {v[i] *= 10;} // v[i] = v[i] * 10;

  for(int i = 0; i < size; i++)

  {cout << v[i] << ", ";}

  cout << endl;

}

/*

g++ Intvector.cpp -o Intvector

./Intvector

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 

0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 

*/

Note:  The function call v.size() is expensive inside a loop, so we store the size of v in an int variable and then refer to this variable inside the loops:

int size = v.size();

for(int i = 0; i < size; i++)

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Exercise 2-8     TCP1, p. 120     (Floatvector)

Exercise 2-8. Create a vector<float> and put 25 floating-point numbers into it using a for loop. Display the vector.

Floatvector.cpp          download

// Creating a vector that holds floats

#include <iostream>

#include <vector>

using std::cout;

using std::endl;

using std::vector;

int main()

{

  vector<float> v;

  for(float f = 0.0; f < 25; f++) // iterate over float with integer values

  {v.push_back(f/2);}

  for(int i = 0, size = v.size(); i < size; i++) // iterate over integer i

  {

    cout << v[i] << ", ";

    if (i == size/2) {cout << endl;}

  }

  cout << endl;

}

/*

g++ Floatvector.cpp -o Floatvector

./Floatvector

0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 

6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 

*/

Note:  Inside the second for() loop, the function call v.size() is executed only once, when the integer size is initialized.

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Exercise 2-9     TCP1, p. 120     (Three float vectors)

Exercise 2-9. Create three vector<float> objects and fill the first two as in the previous exercise (Exercise_2-8). Write a for() loop that adds each corresponding element in the first two vectors and puts the result in the corresponding element of the third vector. Display all three vectors.

vectors.cpp          download

// Creating three vectors that hold floats

#include <iostream>

#include <vector>

using std::cout;

using std::endl;

using std::vector;

int main()

{

  vector<float> v1, v2, v3;

  for(float f = 0.0; f < 15; f++) // iterate over float with integer values

  {

    v1.push_back(f/2);

    v2.push_back(f/3);

  }

  int size = v1.size(); // 15

  for(int i = 0; i < size; i++)

  {v3.push_back(v1[i]+v2[i]);}

  cout << "v1: ";

  for(int i = 0; i < size; i++)

  {

    cout << v1[i] << ", ";

    if (i == size/2) {cout << endl << "    ";}

  }

  cout << endl;

  cout << "v2: ";

  for(int i = 0; i < size; i++)

  {

    cout << v2[i] << ", ";

    if (i == size/2) {cout << endl << "    ";}

  }

  cout << endl;

  cout << "v3: ";

  for(int i = 0; i < size; i++)

  {

    cout << v3[i] << ", ";

    if (i == size/2) {cout << endl << "    ";}

  }

  cout << endl;

}

/*

g++ vectors.cpp -o vectors

./vectors

v1: 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 

    4, 4.5, 5, 5.5, 6, 6.5, 7, 

v2: 0, 0.333333, 0.666667, 1, 1.33333, 1.66667, 2, 2.33333, 

    2.66667, 3, 3.33333, 3.66667, 4, 4.33333, 4.66667, 

v3: 0, 0.833333, 1.66667, 2.5, 3.33333, 4.16667, 5, 5.83333, 

    6.66667, 7.5, 8.33333, 9.16667, 10, 10.8333, 11.6667, 

*/

Note:  v1, v2, v3  have the same size, 15.

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Exercise 2-10     TCP1, p. 120     (SquareFloatvector)

Exercise 2-10. Create a vector<float> and put 25 numbers into it as in the previous exercises. Now square each number and put the result back into the same location in the vector. Display the vector before and after the multiplication.

SquareFloatvector.cpp          download

// Creating a vector that holds floats, then square its values

#include <iostream>

#include <vector>

using std::cout;

using std::endl;

using std::vector;

int main()

{

  float temp;

  vector<float> v;

  for(float f = 0.0; f < 25; f++) // iterate over float with integer values

  {v.push_back(f/2);}

  int size = v.size(); // 25

  for(int i = 0; i < size; i++)

  {

    cout << v[i] << ", ";

    if (i == size/2) {cout << endl;}

  }

  cout << endl;

  for(int i = 0; i < size; i++)

  {

    temp = v[i];

    v[i] = temp * temp;

  }

  for(int i = 0; i < size; i++)

  {

    cout << v[i] << ", ";

    if (i == size/2) {cout << endl;}

  }

  cout << endl;

}

/*

g++ SquareFloatvector.cpp -o SquareFloatvector

./SquareFloatvector

0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 

6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 

0, 0.25, 1, 2.25, 4, 6.25, 9, 12.25, 16, 20.25, 25, 30.25, 36, 

42.25, 49, 56.25, 64, 72.25, 81, 90.25, 100, 110.25, 121, 132.25, 144, 

*/

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