Programming concepts

This article needs to be improved.

Fundamentals are important, so here are some.

Sorting Algorithms

A big topic in computer applications is the quick and efficient sorting of data. There are many different sorting techniques, as a programmer one has to balance the algorithm's ease of reading vs the efficiency of said code. Many standard libraries/APIs already have sorting functions already written, however it is still good practice to know some of the theory behind how the different algorithms work.

Bubble Sort

The bubble sort is a very simple to read algorithm that is the standard first sorting method that most programmers learn. The bubble sort gets its name because values are swapped among each other, gradually moving to the top of the list.

//bubble sort example

#include <stdio.h>
#define SIZE 10

int main( void ){

int a[SIZE] = {2,6,9,1,4,15,7,2}; //array to be sorted

int count; //to be used to count passes

int i; //comparisons counter

int hold; //temp variable to hold numbers

//start of bubble sort

for(count=0; count<SIZE-1; count++){//loop to control number of passes

//size is decreased by 1 to prevent array out of bounds error

for(i=0; i<SIZE-1; i++){//comparison loop

if(a[i]>a[i+1]){//if a[i] bigger than a[i+1], swap values

hold = a[i];

a[i] = a[i+1];

a[i+1] = hold;

}//end if

}//end inner for

}//end outer for

//print array

for(i=0; i<SIZE; i++)

printf("%4d", a[i]);

return 0;

}

Selection Sort

A bit further up on the food chain is the selection sort. The selection sort goes through each element position and finds the value which should occupy the next position in the sorted array. When it finds the appropriate element, the algorithm exchanges it with the valuewhich previously occupied the desired position. On the second pass it looks for the second smallest element and swaps it with the second position and so on.

//Selection sort example

// finds smallest element between left hand and right hand

// moves element to correct position

1. include <stdio.h>

void selectionSort(int array[], int n){

//n is length

int lh, rh, i, temp;

for (lh=0; lh < n; lh++){//everything left of lh is considered sorted

rh = lh; //reset right hand

//runs through lh-rh bounds of array

for (i = lh + 1; i<n; i++){

//if lowest element found, copy index to right hand

if (array[i] < array[rh]) rh = i;

}

//move lowest element to correct position

temp = array[lh];

array[lh] = array[rh];

array[rh] = temp;

}

}

int main( void ){

int len = 8;

int a[8] = {2,6,9,1,4,15,7,2}; //array to be sorted

int i;

selectionSort(a, len);

//print array

for(i=0; i<len; i++)

printf("%4d", a[i]);

return 0;

}

Search Algorithms

Two of the main searching algorithms are Knuth-Morris-Pratt (KMP) and the Boyer-Moore (BM) algorithms.