Shannon Fano encoding and decoding in C: code and output

Code:

#include<stdio.h>

#include<conio.h>

#include<string.h>

struct node

{

char sym[10];

float pro;

int arr[20];

int top;

}s[20];

typedef struct node node;

void prints(int l,int h,node s[])

{

int i;

for(i=l;i<=h;i++)

{

printf("\n%s\t%f",s[i].sym,s[i].pro);

}}

void shannon(int l,int h,node s[])

{

float pack1=0,pack2=0,diff1=0,diff2=0;

int i,d,k,j;

if((l+1)==h || l==h || l>h)

{

if(l==h || l>h)

return;

s[h].arr[++(s[h].top)]=0;

s[l].arr[++(s[l].top)]=1;

return;

}

else

{

for(i=l;i<=h-1;i++)

pack1=pack1+s[i].pro;

pack2=pack2+s[h].pro;

diff1=pack1-pack2;

if(diff1< 0)

diff1=diff1*-1;

j=2;

while(j!=h-l+1)

{

k=h-j;

pack1=pack2=0;

for(i=l;i<=k;i++)

pack1=pack1+s[i].pro;

for(i=h;i>k;i--)

pack2=pack2+s[i].pro;

diff2=pack1-pack2;

if(diff2< 0)

diff2=diff2*-1;

if(diff2>=diff1)

break;

diff1=diff2;

j++;

}

k++;

for(i=l;i<=k;i++)

s[i].arr[++(s[i].top)]=1;

for(i=k+1;i<=h;i++)

s[i].arr[++(s[i].top)]=0;

shannon(l,k,s);

shannon(k+1,h,s);

}

}

int main()

{

int n,i,j;

float x,total=0;

char ch[10];

node temp;

printf("Enter How Many Symbols Do You Want To Enter\t: ");

scanf("%d",&n);

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

{

printf("Enter symbol %d ---> ",i+1);

scanf("%s",ch);

strcpy(s[i].sym,ch);

}

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

{

printf("\n\tEnter probability for %s ---> ",s[i].sym);

scanf("%f",&x);

s[i].pro=x;

total=total+s[i].pro;

if(total>1)

{

printf("\t\tThis probability is not possible.Enter new probability");

total=total-s[i].pro;

i--;

}

}

s[i].pro=1-total;

for(j=1;j<=n-1;j++)

{

for(i=0;i< n-1;i++)

{

if((s[i].pro)>(s[i+1].pro))

{

temp.pro=s[i].pro;

strcpy(temp.sym,s[i].sym);

s[i].pro=s[i+1].pro;

strcpy(s[i].sym,s[i+1].sym);

s[i+1].pro=temp.pro;

strcpy(s[i+1].sym,temp.sym);

}

}

}

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

s[i].top=-1;

shannon(0,n-1,s);

printf("---------------------------------------------------------------");

printf("\n\n\n\tSymbol\tProbability\tCode");

for(i=n-1;i>=0;i--)

{

printf("\n\t%s\t%f\t",s[i].sym,s[i].pro);

for(j=0;j<=s[i].top;j++)

printf("%d",s[i].arr[j]);

}

printf("\n---------------------------------------------------------------");

getch();

return 0;

}

Output: