Implementation of LZW compression algorithm in C?

Answer 1

{

unsigned char **dict;

int *dlength;

unsigned char p[80], temp[80];

char c;

int plength,i,j,k,diff,cd;

plength=1;

cd=256;

p[0]=EOF;

dict= (unsigned char *)malloc(99999); //Allocating memory for Dictionary

if(dict == NULL)

printf("Unable to allocate memory \n");

dlength=(int *)malloc(99999);

for (i = 0; i < 99999; i++) {

dict[i]=(unsigned char *)malloc(60);

if(dict[i]==NULL)

printf("Unable to allocate memory \n");

}

for (i=0;i<256;i++) //loading dictionary with ASCII set

{

dict[i][0]=i;

dlength[i]=1;

}

while ((c = fgetc(Fpt)) != EOF)

{

if(cd==256)

p[0]=(unsigned char *)c;

diff=0;

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

{

for (k=0; k<plength; k++) //checking to see if p+c in dict

{

if(dict[i][k]!=p[k])

diff=1;

}

}

if (diff==0)

{

p[plength]=(unsigned char)c;

plength++;

}

if (diff==1)

{

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

{

for (k=0; k<plength; k++)

{

if(dict[i][k]!=p[k])

diff=1;

}

if (diff==0)

j=i;

}

fputc(j, outfile);

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

{

dict[cd][i]= p[i];

}

dict[cd][plength]=(unsigned char)c;

cd++;

p[0]=c;

}

}

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

{

for (k=0; k<plength; k++)

{

if(dict[i][k]!=p[k])

diff=1;

}

if (diff==0)

j=i;

}

fputc(j, outfile);

fclose(outfile);

fclose(Fpt);

}

By Amit Setia