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。

/***********************************************************************************************************

RLE.c

本演示程序提供了RLE的压缩和解压缩函数

**********************************************************************************************************/

#include

#include

#include

/* 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);

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;

}

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！！！