RLE算法变体C语言实现

RLE算法：这种压缩编码是一种变长的编码，RLE根据文本不同的具体情况会有不同的压缩编码变体与之相适应，以产生更大的压缩比率。

  变体：重复次数+字符

  文本字符串：A A A B B B C C C C D D D D，编码后得到：3 A 3 B 4 C 4 D。

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  以上算法比较适合重复次数比较多的文件，否则不但不能达到压缩的效果，反而使文件倍增！！！

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* 函数原型 */
int RLE_Compression(char * infile_name, char * outfile_name);
int RLE_Decompression(char * infile_name, char * outfile_name);
/* 主程序 */
void main(int argc, char *argv[])
{
    printf("RLE compression and decompression utility\n");
    if (4 != argc)
    {
        printf("\nUsage : rle -c|d sourcefilename targetfilename\n");
        exit(0);
    }
    if (! strcmp(argv[1], "-c"))
    {
        printf("\nCompress...");
        RLE_Compression(argv[2], argv[3]);
    }
    else if (! strcmp(argv[1], "-d"))
    {
        printf("\nDecompress...");
        RLE_Decompression(argv[2], argv[3]);
    }
    else
        printf("\nUnknow command.\n");
}
/**************************************************************************
RLE_Decompression ()
本函数用RLE算法对文件进行解压缩
**************************************************************************/
int RLE_Decompression(char * infile_name, char * outfile_name)
{
    register int seq_len, i;
    char scratch_space[255],cur_char;
    FILE *infile, *outfile;
    if ((infile=fopen(infile_name, "rb")) == NULL)
    {
        strcpy(scratch_space, "Unable to open ");
        strcat(scratch_space, infile_name);
        <mce:script type="text/javascript" src="http://hi.images.csdn.net/js/blog/tiny_mce/themes/advanced/langs/zh.js" mce_src="http://hi.images.csdn.net/js/blog/tiny_mce/themes/advanced/langs/zh.js"></mce:script><mce:script type="text/javascript" src="http://hi.images.csdn.net/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js" mce_src="http://hi.images.csdn.net/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js"></mce:script>puts(scratch_space);
        return 1;
    }
    if ((outfile=fopen(outfile_name, "wb")) == NULL)
    {
        strcpy(scratch_space, "Unable to open ");
        strcat(scratch_space, outfile_name);
        puts(scratch_space);
        return 1;
    }
    if ( feof(infile) )
    {
        return 0;
    }
    while (!feof(infile))
    {
        seq_len = (int)fgetc( infile );
        cur_char = fgetc( infile );
        for ( i = 0; i < seq_len; i++ )
        {
            fputc( cur_char, outfile );
        }
    }
    fclose(infile);
    fclose(outfile);
    return 0;
}
/**************************************************************************
RLE_Compression ()
本函数用RLE算法对文件进行压缩
**************************************************************************/
int RLE_Compression(char * infile_name, char * outfile_name)
{
    register int seq_len;
    char scratch_space[255],cur_char, cur_seq;
    FILE *infile, *outfile;
    if ((infile=fopen(infile_name, "rb")) == NULL)
    {
        strcpy(scratch_space, "Unable to open ");
        strcat(scratch_space, infile_name);
        puts(scratch_space);
        return 1;
    }
    if ((outfile=fopen(outfile_name, "wb")) == NULL)
    {
        strcpy(scratch_space, "Unable to open ");
        strcat(scratch_space, outfile_name);
        puts(scratch_space);
        return 1;
    }
    if ( feof(infile) )
    {
        return 0;
    }
    cur_char = fgetc(infile);
    cur_seq = cur_char;
    seq_len = 1;
    while (!feof(infile))
    {
        cur_char = fgetc(infile);
        if ( cur_char == cur_seq )
        {
            seq_len++;
        }
        else
        {
            fputc( seq_len, outfile );
            fputc( cur_seq, outfile );
            cur_seq = cur_char;
            seq_len = 1;
        }
    }
    fclose( infile );
    fclose( outfile );
    return 0;
}