compress.h

哈弗曼编码

#include "iostream.h"

bool compress(char *);
bool extract(char *);

struct compress
{
	unsigned a:1;
	unsigned b:1;
	unsigned c:1;
	unsigned d:1;
	unsigned e:1;
	unsigned f:1;
	unsigned g:1;
	unsigned h:1;
};
typedef struct compress COMPRESS;

bool compress(char *_file_to_compress)
{
	FILE *file_to_compress,*file_compressed;
	char c;															//存放从待压缩的文件中读取字符
	COMPRESS compressed_array[ARRAY_LENGTH];
	int line_of_compressed_array=0;
	int effective_number_of_last_byte=0;
	file_to_compress=fopen(_file_to_compress,"rt");
	if (file_to_compress==NULL)
		return false;
	file_compressed=fopen("zip.txt","wb");
	while(!feof(file_to_compress))
	{
		c=fgetc(file_to_compress);
		if (c!='1' && c!='0' && c!=-1)
		{
			cout<<"The file contains illegal character (not 0 or 1) !"<<endl;
			return false;
		}
		else
		{
			if (c==-1)
				break;
			switch(effective_number_of_last_byte)
			{
			case 0:
				if (c=='1')
					compressed_array[line_of_compressed_array].a=1;	
				else
					compressed_array[line_of_compressed_array].a=0;
				effective_number_of_last_byte++;
				break;
			case 1:
				if (c=='1')
					compressed_array[line_of_compressed_array].b=1;	
				else
					compressed_array[line_of_compressed_array].b=0;
				effective_number_of_last_byte++;
				break;
			case 2:
				if (c=='1')
					compressed_array[line_of_compressed_array].c=1;	
				else
					compressed_array[line_of_compressed_array].c=0;
				effective_number_of_last_byte++;
				break;
			case 3:
				if (c=='1')
					compressed_array[line_of_compressed_array].d=1;	
				else
					compressed_array[line_of_compressed_array].d=0;
				effective_number_of_last_byte++;
				break;
			case 4:
				if (c=='1')
					compressed_array[line_of_compressed_array].e=1;	
				else
					compressed_array[line_of_compressed_array].e=0;
				effective_number_of_last_byte++;
				break;
			case 5:
				if (c=='1')
					compressed_array[line_of_compressed_array].f=1;	
				else
					compressed_array[line_of_compressed_array].f=0;
				effective_number_of_last_byte++;
				break;
			case 6:
				if (c=='1')
					compressed_array[line_of_compressed_array].g=1;	
				else
					compressed_array[line_of_compressed_array].g=0;
				effective_number_of_last_byte++;
				break;
			case 7:
				if (c=='1')
					compressed_array[line_of_compressed_array].h=1;	
				else
					compressed_array[line_of_compressed_array].h=0;
				line_of_compressed_array++;
				effective_number_of_last_byte=0;
				break;
			default:
				break;
			}
		}
	}
	effective_number_of_last_byte--;
	fprintf(file_compressed,"%d,%d",line_of_compressed_array,effective_number_of_last_byte);
	int j=0;
	COMPRESS *q=compressed_array;
	while(j<=line_of_compressed_array)
	{
		fwrite(q,1,1,file_compressed);
		q=q+1;
		j++;
	}
	fclose(file_compressed);
	fclose(file_to_compress);
	char anwser;
	cout<<"Have a look at the file?"<<endl;
	cin>>anwser;
	if (anwser=='y')
		system("notepad.exe file_compressed.txt");
	return true;
}

bool extract(char *_file_compressed)
{
	FILE *file_compressed,*extract_file;
	int line_of_compressed_array=0,i=0;
	int effective_number_of_last_byte=0;
	COMPRESS compressed_array[ARRAY_LENGTH],p,*q;
	q=compressed_array;
	file_compressed=fopen(_file_compressed,"rb");
	if (file_compressed==NULL)
	{
		cout<<"The compressed file doesn't exist !"<<endl;
		return false;
	}
	fscanf(file_compressed,"%d,%d",&line_of_compressed_array,&effective_number_of_last_byte);
	extract_file=fopen("extract.txt","wt");
	while(!feof(file_compressed))
	{
		fread(&p,1,1,file_compressed);
		q->a=p.a;
		q->b=p.b;
		q->c=p.c;
		q->d=p.d;
		q->e=p.e;
		q->f=p.f;
		q->g=p.g;
		q->h=p.h;
		q=q+1;
	}
	while(i<line_of_compressed_array)
	{
		if (compressed_array[i].a==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].b==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].c==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].d==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].e==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].f==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].g==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		if (compressed_array[i].h==1)
			fputc('1',extract_file);
		else
			fputc('0',extract_file);
		i++;
	}
	if (effective_number_of_last_byte>=0)					//大于等于零说明还有不满一字节的数据未写入
	{
		i=0;
		switch(effective_number_of_last_byte)
		{
		default:
			if (compressed_array[line_of_compressed_array].a==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].b==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].c==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].d==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].e==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].f==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].g==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
		i++;
		if (i>effective_number_of_last_byte)
			break;
			if (compressed_array[line_of_compressed_array].h==1)
				fputc('1',extract_file);
			else
				fputc('0',extract_file);
			break;
		}
	}
	fputc(-1,extract_file);
	fclose(file_compressed);
	fclose(extract_file);
	char anwser;
	cout<<"Have a look at the file (y or n) ?"<<endl;
	cin>>anwser;
	if (anwser=='y')
		system("notepad.exe extract.txt");
	return true;
}