Tag Archives: #e7e7e7

#mastery21 #TC1017

Posted on 06/05/2015 by Mitzi Hernandez | Comments Off

Use of recursion for repetitive algorithms

What is recursion? The simple answer is, it’s when a function calls itself. But how does this happen? Why would this happen, and what are its uses?

When we talk about recursion, we are really talking about creating a loop. Let’s start by looking at a basic loop.

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for(int i=0; i

cout “The number is: “

}

For those who don’t yet know, this basic loop displays the sentence, “The number is: ” followed by the value of ‘i’. Like this.

#E7E7E7; padding: .75pt .75pt .75pt .75pt;” valign=”top”>

The number is: 0

The number is: 1

The number is: 2

The number is: 3

The number is: 4

The number is: 5

The number is: 6

The number is: 7

The number is: 8

The number is: 9

Inside the ‘for loop’ declaration we have the integer variable ‘i’ and have its starting value of 0. So the first time the sentence is displayed it reads, “The number is: 0”. The part of the ‘for loop’ declaration that is ‘i++’ tells the program that each time the loop repeats, the value of ‘i’ should be increased by 1. So, the next time the sentence is displayed it reads, “The number is: 1”.
This cycle will continue to repeat for as long as the value of ‘i’ is less than 10. The last sentence displayed would read, “The number is: 9”. As you can see the basic ‘for loop’ has three parts to its declaration, a starting value, what must remain true in order to continue repeating, and a modifying expression. Everything that is contained within the {braces} is what the program performs. Cout stands for console out, and prints words or characters to the screen.
So what does this have to do with recursion? Remember recursion is a loop. What if I did not want to just print a message to the screen? A loop can be used to perform other tasks as well.

In the following code is the same loop as above only now it is being used to call a function.

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#include

using namespace std;

void numberFunction(int i) {

cout “The number is: “

}

int main() {

for(int i=0; i

numberFunction(i);

}

return 0;

}

Edit & Run

I have declared a void function, which means it returns nothing, and takes a parameter of ‘int i’. The function is named ‘numberFunction’ and as you can see, all it does is display the sentence, “The number is: ” followed by the current value of ‘i’. The function is called into use by the ‘for loop’, which continually calls the function as long as the value of ‘i’ is less than 10.

Now with recursion, we won’t need to use a ‘for loop’ because we will set it up so that our function calls itself. Let’s recreate this same program one more time, only this time we will do it without a ‘for loop’. We will use a recursion loop instead, like this.

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#include

using namespace std;

void numberFunction(int i) {

cout “The number is: “

i++;

if(i

numberFunction(i);

}

int main() {

int i = 0;

numberFunction(i);

return 0;

}

Edit & Run

We did it! We used recursion! You can see the call to ‘numberFunction’ is made only once in the main part of the program but it keeps getting called again and again from within the function itself, for as long as ‘i’ is less than 10.

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Posted in Blogs, Syndicated, TC1017 Blogs

Tagged #000070, #0000b0, #333333, #500070, #600030, #a0a0a0, #c, #c0c0d0, #e7e7e7, #efefff, #include, #mastery21, #TC, #TC1017, Mastery

Mastery 23

Posted on 06/05/2015 by Mauricio Cooper | Comments Off

Creation and use of vectors in C++

Vector

Vectors are sequence containers representing arrays that can change in size.

Just like arrays, vectors use contiguous storage locations for their elements, which means that their elements can also be accessed using offsets on regular pointers to its elements, and just as efficiently as in arrays. But unlike arrays, their size can change dynamically, with their storage being handled automatically by the container.

Internally, vectors use a dynamically allocated array to store their elements. This array may need to be reallocated in order to grow in size when new elements are inserted, which implies allocating a new array and moving all elements to it. This is a relatively expensive task in terms of processing time, and thus, vectors do not reallocate each time an element is added to the container.

Example

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// constructing vectors
#include 
#include 

int main ()
{
  // constructors used in the same order as described above:
  std::vectorint> first;                                // empty vector of ints
  std::vectorint> second (4,100);                       // four ints with value 100
  std::vectorint> third (second.begin(),second.end());  // iterating through second
  std::vectorint> fourth (third);                       // a copy of third

  // the iterator constructor can also be used to construct from arrays:
  int myints[] = {16,2,77,29};
  std::vectorint> fifth (myints, myints + sizeof(myints) / sizeof(int) );

  std::cout "The contents of fifth are:";
  for (std::vectorint>::iterator it = fifth.begin(); it != fifth.end(); ++it)
    std::cout ' ' 'n';

  return 0;
}

#c0c0d0; width: 16px; height: 16px; border-top-right-radius: 3px; border-bottom-right-radius: 3px;”>Edit & Run

Output:

#e7e7e7;”>

The contents of fifth are: 16 2 77 29

Credits:

http://www.cplusplus.com/reference/vector/vector/vector/

http://www.cplusplus.com/reference/vector/vector/

#TC1017 #Mastery23

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Posted in Blogs, Syndicated, TC1017 Blogs

Tagged #000070, #0000b0, #007000, #333333, #500070, #600030, #a0a0a0, #c0c0d0, #e7e7e7, #efefff, #include, #Mastery23, #TC, #TC1017, Mastery

Mastery 21

Posted on 06/05/2015 by Mauricio Cooper | Comments Off

Use of recursion for repetitives algorithms

What is recursion? The simple answer is, it’s when a function calls itself. But how does this happen? Why would this happen, and what are its uses?

When we talk about recursion, we are really talking about creating a loop. Let’s start by looking at a basic loop.

#a0a0a0; text-align: right; vertical-align: top; min-width: 20px;”>

1
2
3

#c0c0d0; vertical-align: top; background: #efefff;”>

for(int i=0;  i"The number is: "

For those who don’t yet know, this basic loop displays the sentence, “The number is: ” followed by the value of ‘i’. Like this.

#e7e7e7;”>


The number is: 0
The number is: 1
The number is: 2
The number is: 3
The number is: 4
The number is: 5
The number is: 6
The number is: 7
The number is: 8
The number is: 9

Credit:

http://www.cplusplus.com/articles/D2N36Up4/

#TC1017 #Mastery21

Comments Off on Mastery 21

Posted in Blogs, Syndicated, TC1017 Blogs

Tagged #0000b0, #600030, #a0a0a0, #c0c0d0, #e7e7e7, #efefff, #mastery21, #TC, #TC1017, Mastery

Mastery 12

Posted on 06/04/2015 by Mauricio Cooper | Comments Off

Creating functions in C++

Functions

Functions allow to structure programs in segments of code to perform individual tasks.

In C++, a function is a group of statements that is given a name, and which can be called from some point of the program. The most common syntax to define a function is:

type name ( parameter1, parameter2, ...) { statements }
Where:
– type is the type of the value returned by the function.
– name is the identifier by which the function can be called.
– parameters (as many as needed): Each parameter consists of a type followed by an identifier, with each parameter being separated from the next by a comma. Each parameter looks very much like a regular variable declaration (for example:int x), and in fact acts within the function as a regular variable which is local to the function. The purpose of parameters is to allow passing arguments to the function from the location where it is called from.
– statements is the function’s body. It is a block of statements surrounded by braces { } that specify what the function actually does.

// function example
#include <iostream>
using namespace std;

int subtraction (int a, int b)
{
  int r;
  r=a-b;
  return r;
}

int main ()
{
  int x=5, y=3, z;
  z = subtraction (7,2);
  cout << "The first result is " << z << 'n';
  cout << "The second result is " << subtraction (7,2) << 'n';
  cout << "The third result is " << subtraction (x,y) << 'n';
  z= 4 + subtraction (x,y);
  cout << "The fourth result is " << z << 'n';
}

The first result is 5
The second result is 5
The third result is 2
The fourth result is 6

#TC1017 #Mastery12

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Posted in Blogs, Syndicated, TC1017 Blogs

Tagged #0000b0, #007000, #204080, #500070, #600030, #c0c0d0, #e7e7e7, #efefff, #include, #mastery12, #TC1017

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