Software Engineering 14

Programming in C

Class Syllabus #4

Bubble Sort, String reading, ctype.h,strlen(),strcmp(), ? : operator, the need for functions, #ifdef #endif

/*bubleSort.c*/

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

//#define DEBUG

#define MAX_NUMBERS 1000

#define MAX_BUFFER 256

int main()

{

double data[MAX_NUMBERS];//this array is the actual data

int n=0;//this is the number of data elements

char inString[MAX_BUFFER];//used to input numbers

int dotPos;//signifies the position of the dot in the number (###.####), -1 if no dot

double pow; //helps convert string to float

int i,j;//iterators

char numFlag=1;//signifies when to leave input loop

double temp;//for switch in buble sort

printf("ENTER REAL POSITIVE NUMBERS.\n"

"(TO STOP ENTERING THE NUMBERS ENTER A NON-DIGIT CHARACTER)\n");

while(numFlag & n<=MAX_NUMBERS)//this is the input loop
{
/*Some think it's nice to write:1'st
2'nd
3'rd

4'th 5'th 6'th...... */

printf("Enter the %d'%s number: ",n+1,

1==n+1 ? "st" : (2==n+1 ? "nd" : (3==n+1 ? "rd" : "th")) );

scanf("%s",inString);

#ifdef DEBUG
printf("***%s***\n",inString);
#endif

for(dotPos=0; inString[dotPos]!='.' & inString[dotPos]; dotPos++) /**/;

//above loop finds dotPos if exists

data[n]=0.00;//start of with 0

for(pow=1, i=dotPos-1; i>=0 ; i--,pow*=10)

if(isdigit(inString[i]) )

data[n]+=pow * (inString[i]-'0');

else

{

numFlag=0;//if it was a non-digit number time to quit

break;

}

for(pow=0.1, i=dotPos+1; i<(signed int)strlen(inString);i++, pow /=10)

if(isdigit(inString[i]) )

data[n]+=pow * (inString[i]-'0');

else

{

numFlag=0;//if it was a non-digit number time to quit

break;

}

if(strcmp(".",inString) == 0 )

numFlag=0;//handle extreme case of "." string

#ifdef DEBUG

printf("%lf\n",data[n]);

#endif

n++;

}n--;//decrement because last num did not count

if(!n)

exit(0);//nothing to sort and print

#ifdef DEBUG

printf("These are the numbers entered:\n");

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

printf("%lf\t",data[i]);

putchar('\n');

#endif

/*performs the bubble sort*/

for(i=0; i<n-1 ; i++) //loop on whole array

for(j=n-1;j>i;j--) //loop on the top i slots

if(data[j-1] > data[j])

{/*switch*/

temp=data[j-1];

data[j-1]=data[j];

data[j]=temp;

}

printf("Here is the sorted list:\n");

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

printf("%d:\t%g\n",i+1,data[i]);

return 0;//all ok

}//end of main

Multidimensional array operations, using logical expressions

/*matrix.c*/
#include <stdio.h>
#define HEIGHT 4
#define WIDTH 3
#define SMOOTHING "The matrix is smoothed by averaging each cell with it's neighbors:"

void main()

{

int row,col;

float matrix[HEIGHT][WIDTH];

float smoothMatrix[HEIGHT][WIDTH];

float fakePadding[WIDTH];//formally important to insure that smoothing will

//not cause overflow

for(row=0; row < HEIGHT; row++)//get matrix from user

{

printf("Enter %d real numbers for row #%d (separated by white space):",WIDTH,row+1);

for(col=0;col < WIDTH; col++)

scanf("%f",&matrix[row][col]);

fflush(stdin);//so that if user entered more than needed it will not disturb

}

printf(SMOOTHING"\n");

for(row=0;row<HEIGHT;row++)

for(col=0;col<WIDTH;col++)//loop on each element of matrix

{

smoothMatrix[row][col]=

(row!=0)* ((col!=0)*matrix[row-1][col-1]+matrix[row-1][col]+(col!=WIDTH-1)*matrix[row-1][col+1])+

((col!=0)*matrix[row][col-1] +matrix[row][col]+ (col!=WIDTH-1)*matrix[row][col+1])+

(row!=HEIGHT-1)*((col!=0)*matrix[row+1][col-1]+matrix[row+1][col]+(col!=WIDTH-1)*matrix[row+1][col+1]);

smoothMatrix[row][col]/=9 - 3*(0==row) -3*(HEIGHT-1 == row) -

3* (0==col)-3*(WIDTH-1==col) + (0==row & 0 ==col)

+ (0==row & WIDTH-1==col) + (HEIGHT-1==row & 0==col)

+ (HEIGHT-1 == row & WIDTH-1 == col);

}

for(row=0;row<HEIGHT;row++)//print the smoothed matrix

for(col=0;col<WIDTH;col++)

printf("%g%c",smoothMatrix[row][col],(col + 1) % 3 ? '\t' : '\n');

//every WIDTH collumn print \n instead of \t

}

Basic String operations

/*squeezeString.c*/

#include <stdio.h>
#include <string.h>
#define STRING_SIZE 0xffff //32K
void main()
{
int s,c,len=0;
char string[STRING_SIZE];
char compress[STRING_SIZE*2];//can expand twice at worst case
//loop untill room is out or end of file is reached

while( len<STRING_SIZE-1 & (string[len++]=getchar()) != EOF);

string[--len]='\0';//cap off the string where EOF was put (we loose last char if non EOF)

//now len signfies length of string

s=0;c=0;

while(string[s])//loop on string and squeeze it

{

compress[c]=string[s];

compress[c+1]=0;

compress[c+1]++;

while(string[++s]==compress[c]);

c+=2;

}

compress[--c]='\0';//cap compress ( c is now the compressed size)

printf("Original size: %d\n"

"Compressed size: %d\n",len,c);

printf("This is a printout, taken from the compressed string:\n");

for(s=0;compress[s-1];s+=2)

for(c=0;c<compress[s+1];c++)

putchar(compress[s]);

}

Output

D:\Yoni\C_course\squeezeString\Debug>sq.exe < good.txt

Original size: 209

Compressed size: 75

:This is a printout, taken from the compressed string

aaa

aaaa

bbbbb

cccccc

ddddddd

eeeeeeee

fffffffff

gggggggggg

hhhhhhhhhhh

iiiiiiiiiiii

jjjjjjjjjjjjj

kkkkkkkkkkkkkk

lllllllllllllll

mmmmmmmmmmmmmmmm

nnnnnnnnnnnnnnnnn

oooooooooooooooooo

ppppppppppppppppppp

>D:\Yoni\C_course\squeezeString\Debug