Thread: For loop leads to segmentation fault

hello everyone,

little code of mine. problem not written @ title of thread, there more.

first of all, here code (if need know file process contains, post information too):

code:

#include <iostream> #include <zlib.h> #include <fstream>  using namespace std;  z_stream z;  int _decompress(bytef * in_data, long in_size, bytef * out_data, long * out_size){      int status;          z.avail_in = in_size;     z.next_in = in_data;          z.avail_out = *out_size;     z.next_out = out_data;      status = inflateinit(&z);    //segmentation fault      if ( status != z_ok )         return status;          if ( z.avail_in != 0 && *out_size != 0 ) {         status = inflate( &z, z_no_flush );    //segmentation fault         if ( status < 0 ){             cout << "error: " << status << endl;             return -11;         }         else if ( status == z_ok && *out_size > 0 ){             cout << "not enough output space!\n";             return -12;         }      }else if( *out_size != 0 ){         cout << "no input?\n";         return -10;     }          while ( status == z_ok  ) {                  *out_size += 1024;         z.avail_out = *out_size;         delete out_data;         out_data = new bytef[*out_size];         z.next_out = out_data;                  status = inflate( &z, z_no_flush );    //segmentation fault     }          if ( status != z_stream_end );         cout << "final error: " << status << endl;      (void)inflateend(&z);          return status; }     int main(){     ifstream fp_in;     fp_in.open("r.0.0.mcr", ios::in);          char *a = new char[5];        for(int = 0; i<1024; i++){                   fp_in.seekg(i*4);         fp_in.read(a, 4);          cout << << ":";                  if((int)a[0]!=0 || (int)a[1]!=0 || (int)a[2]!=0 || (int)a[3]!=0){                          cout     << (i+1)%32                      << "x"                      << (i+1)/32                      << " ( pos: "                      << (  (int)(unsigned char)a[0]*65536                          + (int)(unsigned char)a[1]*255                          + (int)(unsigned char)a[2]            )*4096                      << " size: ";              fp_in.seekg((      (int)(unsigned char)a[0]*65536                               + (int)(unsigned char)a[1]*256                               + (int)(unsigned char)a[2]            )*4096);                           fp_in.read(a,5);              long size =   (int)(unsigned char)a[0]*16777216                          + (int)(unsigned char)a[1]*65536                          + (int)(unsigned char)a[2]*256                          + (int)(unsigned char)a[3];                          cout << (int)(unsigned char)a[0] << ":" ;        //problem cout             cout << (int)(unsigned char)a[1] << ":" ;             cout << (int)(unsigned char)a[2] << ":" ;             cout << (int)(unsigned char)a[3] << " = ";              cout << size << " ) \t:";              char *buff = new char[size-1];              long out_size = 0;              bytef *out;                          fp_in.read(buff,size-1);             int status = _decompress((bytef*)buff,size-1,out,&out_size);              if(status>=0)                 cout << "decompressed size: " << out_size << " bytes.";             else                 cout << "error: " << status;         }         cout << endl;     }      for(int = 0; i<1024; i++)        //segmentation fault         cout << "anything";           fp_in.close();      return 0; }

so, here problems have

1) [solved] i not understand why can not put z_stream z; inside int _decompress function. if do, 3 methods inside have "segmentation fault" comment produce kind of error (during runtime.)

2) @ 5 lines "problem cout" comment, if attempt in 1 line weird error think zlib, , not g++.

3) @ end, there loop. loop produces segmentation fault well. if remove it, fine. tried remove contents of loop above it. segmentation fault gone well.

appreciate any of these problems!

in advance!

posted sakishrist

1) not understand why can not put z_stream z; inside int _decompress function. if do, 3 methods inside have "segmentation fault" comment produce kind of error (during runtime.)

a struct defined @ global scope automatically zero-initialised; 1 defined in function body not. zero-initialising presumably set zalloc , zfree null rather undefined values have if not zero-initialised (note zlib docs state zalloc , zfree must set prior call inflateinit(...), , null acceptable value them.)

edit:

also, "out" doesn't seem initialised inside main().

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