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  1. #include <stdlib.h>
  2. #include <string.h>
  3. #include <stdio.h>
  4. #include <ctype.h>
  5.  
  6.  
  7.  
  8. // for MSVC
  9. #ifdef _WIN32
  10.     #define snprintf sprintf_s
  11. #endif
  12.  
  13.  
  14.  
  15. int pack( char const * SrcStr, char * DstBuf, size_t DstBuf_Size ) {
  16.  
  17.     int Err = 0;
  18.  
  19.     char const * Src_Ptr = SrcStr;
  20.     char * Dst_Ptr = DstBuf;
  21.  
  22.     size_t SrcBuf_Size = strlen( SrcStr ) + 1;
  23.     char const * SrcBuf_End = SrcStr + SrcBuf_Size;
  24.     char const * DstBuf_End = DstBuf + DstBuf_Size;
  25.  
  26.     char c = 0;
  27.     int RepeatCount = 1;
  28.  
  29.     // don't forget about buffers intercrossing
  30.     if( !SrcStr || !DstBuf || 0 == DstBuf_Size || (DstBuf < SrcBuf_End && DstBuf_End > SrcStr) ) {
  31.         return 1;
  32.     }
  33.  
  34.     // source string must contain no digits
  35.     // check for destination buffer overflow
  36.     while( '\0' != *Src_Ptr && Dst_Ptr < DstBuf_End - 1 && !isdigit( *Src_Ptr ) && !Err ) {
  37.  
  38.         c = *Dst_Ptr = *Src_Ptr;
  39.         ++Src_Ptr; ++Dst_Ptr;
  40.  
  41.         for( RepeatCount = 1; *Src_Ptr == c; ++RepeatCount ) {
  42.             ++Src_Ptr;
  43.         }
  44.  
  45.         if( RepeatCount > 1 ) {
  46.             int res = snprintf( Dst_Ptr, DstBuf_End - Dst_Ptr - 1, "%i", RepeatCount );
  47.             if( res < 0 ) {
  48.                 Err = 1;
  49.             } else {
  50.                 Dst_Ptr += res;
  51.                 RepeatCount = 1;
  52.             }
  53.        }
  54.     }
  55.  
  56.     *Dst_Ptr = '\0';
  57.  
  58.     return Err;
  59. };
  60.  
  61. int unpack( char const * SrcStr, char * DstBuf, size_t DstBuf_Size ) {
  62.  
  63.     int Err = 0;
  64.  
  65.     char const * Src_Ptr = SrcStr;
  66.     char * Dst_Ptr = DstBuf;
  67.  
  68.     size_t SrcBuf_Size = strlen( SrcStr ) + 1;
  69.     char const * SrcBuf_End = SrcStr + SrcBuf_Size;
  70.     char const * DstBuf_End = DstBuf + DstBuf_Size;
  71.  
  72.     char c = 0;
  73.  
  74.     // don't forget about buffers intercrossing
  75.     // first character of source string must be non-digit
  76.     if( !SrcStr || !DstBuf || 0 == DstBuf_Size || (DstBuf < SrcBuf_End && DstBuf_End > SrcStr) \
  77.         || isdigit( SrcStr[0] ) ) {
  78.  
  79.         return 1;
  80.     }
  81.  
  82.     // check for destination buffer overflow
  83.     while( '\0' != *Src_Ptr && Dst_Ptr < DstBuf_End - 1 && !Err ) {
  84.  
  85.         if( !isdigit( *Src_Ptr ) ) {
  86.             c = *Dst_Ptr = *Src_Ptr;
  87.             ++Src_Ptr; ++Dst_Ptr;
  88.  
  89.         } else {
  90.             int repeat_count = strtol( Src_Ptr, (char**)&Src_Ptr, 10 );
  91.             if( !repeat_count || repeat_count - 1 > DstBuf_End - Dst_Ptr - 1 ) { 
  92.                 Err = 1;
  93.             } else {
  94.                 memset( Dst_Ptr, c, repeat_count - 1 );
  95.                 Dst_Ptr += repeat_count - 1;
  96.             }
  97.         }
  98.     }
  99.  
  100.     *Dst_Ptr = '\0';
  101.  
  102.     return Err;
  103. };
  104.  
  105. int main() {
  106.  
  107.     char str[] = "aabbbccccddddd";
  108.     char buf1[128] = {0};
  109.     char buf2[128] = {0};
  110.  
  111.     pack( str, buf1, 128 );
  112.     printf( "pack: %s -> %s\n", str, buf1 );
  113.  
  114.     unpack( buf1, buf2, 128 );
  115.     printf( "unpack: %s -> %s\n", buf1, buf2 );
  116.  
  117.     return 0;
  118. }
Success #stdin #stdout 0s 2292KB
comments (?)
stdin 
Standard input is empty
stdout 
pack: aabbbccccddddd -> a2b3c4d5
unpack: a2b3c4d5 -> aabbbccccddddd
https://ideone.com/Y7FNE3
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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