用C语言简单演示如何借助zlib库实现文件的压缩和解压缩

用C语言简单演示如何借助zlib库实现文件的压缩和解压缩

最近需要用到zlib压缩，解压，写了一个简单的测试demo，记录如下：

#include 
#include 
#include 


// Demonstration of zlib utility functions
unsigned long file_size(char *filename)
{
   FILE *pFile = fopen(filename, "rb");
   fseek (pFile, 0, SEEK_END);
   unsigned long size = ftell(pFile);
   fclose (pFile);
   return size;
}


int decompress_one_file(char *infilename, char *outfilename)
{

   int num_read = 0;
   char buffer[128] = {0};

   gzFile infile = gzopen(infilename, "rb");
   FILE *outfile = fopen(outfilename, "wb");

   if (!infile || !outfile){
        return -1;
   }

   while ((num_read = gzread(infile, buffer, sizeof(buffer))) > 0) {
      fwrite(buffer, 1, num_read, outfile);
      memset(buffer,0,128);
    }
   gzclose(infile);
   fclose(outfile);
   return 0;
}


int compress_one_file(char *infilename, char *outfilename)
{
    int num_read = 0;
   char inbuffer[128] = {0};
   unsigned long total_read = 0, total_wrote = 0;
   FILE *infile = fopen(infilename, "rb");
   gzFile outfile = gzopen(outfilename, "wb");
   if (!infile || !outfile){
        return -1;
   } 

   while ((num_read = fread(inbuffer, 1, sizeof(inbuffer), infile)) > 0) {
      total_read += num_read;
      gzwrite(outfile, inbuffer, num_read);
      memset(inbuffer,0,128);
   }
   fclose(infile);
   gzclose(outfile);
   printf("Read %ld bytes, Wrote %ld bytes,"
          "Compression factor %4.2f%%\n",
      total_read, file_size(outfilename),
      (1.0-file_size(outfilename)*1.0/total_read)*100.0);
   return 0;
}


int main(int argc, char **argv)
{
   compress_one_file(argv[1],argv[2]);
   //decompress_one_file(argv[1],argv[2]);
   return 0;
}

编译

gcc zlibcompress.c -o zlibcompress -lz