Problem with assure(out, "macro.out");

[Peter1234]

I am using C++ Builder to study C++. When I apply the code listed below, sometimes the macro is created with results. Other times the macro file is empty and the error message reads "access violation at 0x7c90eddc: write of address 0x000e0f1c' Process stopped. Use Step or Run to continue". I can see the referemce on the CPU window but I have no ide what to do. STEP or RUN do not work and I have to press CONT ALT DEL to close C++ Builder. I have tested and verified that the problem is caused by line 8.

#include "C:\general\require.h"
#include <fstream>
using namespace std;
#define BAND(x) (((x)>5 && (x)<10) ? (x) : 0)

int main() {
ofstream out("macro.out");
assure(out, "macro.out");
for(int i = 4; i < 11; i++) {
int a = i;
out << "a = " << a << endl << '\t';
out << "BAND(++a)=" << BAND(++a) << endl;
out << "\t a = " << a << endl;
}
} ///:~ 

[Bazzy]

What does 'assure' do?

[Peter1234]

The code for assure is in require.h

//: :require.h
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
// Test for error conditions in programs
// Local "using namespace std" for old compilers
#ifndef REQUIRE_H
#define REQUIRE_H
#include <cstdio>
#include <cstdlib>
#include <fstream>

inline void require(bool requirement, 
  const char* msg = "Requirement failed") {
  using namespace std;
  if (!requirement) {
    fputs(msg, stderr);
    fputs("\n", stderr);
    exit(1);
  }
}

inline void requireArgs(int argc, int args, 
  const char* msg = "Must use %d arguments") {
  using namespace std;
   if (argc != args + 1) {
     fprintf(stderr, msg, args);
     fputs("\n", stderr);
     exit(1);
   }
}

inline void requireMinArgs(int argc, int minArgs,
  const char* msg = 
    "Must use at least %d arguments") {
  using namespace std;
  if(argc < minArgs + 1) {
    fprintf(stderr, msg, minArgs);
    fputs("\n", stderr);
    exit(1);
  }
}
  
inline void assure(std::ifstream& in, 
  const char* filename = "") {
  using namespace std;
  if(!in) {
    fprintf(stderr,
      "Could not open file %s\n", filename);
    exit(1);
  }
}

inline void assure(std::ofstream& in, 
  const char* filename = "") {
  using namespace std;
  if(!in) {
    fprintf(stderr,
      "Could not open file %s\n", filename);
    exit(1);
  }
}
#endif // REQUIRE_H ///:~ 

[Peter1234]

Just in case some one is trying to help, the program runs after adding line 3:
#include <queue>
Now I have to understand the problem and the solution.

#include "C:\general\require.h"
#include <fstream>
#include <queue>
using namespace std;
#define BAND(x) (((x)>5 && (x)<10) ? (x) : 0)

int main() {
ofstream out("macro.out");
assure(out, "macro.out");
for(int i = 4; i < 11; i++) {
int a = i;
out << "a = " << a << endl << '\t';
out << "BAND(++a)=" << BAND(++a) << endl;
out << "\t a = " << a << endl;
}

} ///:~

[guestgulkan]

I can't see what on earth queue has got to do with this at all.

(I'm going to have a look at that book)

[Peter1234]

When the program fails the error message is:

"access violation at 0x7c90eddc: write of address 0x000e0f1c' Process stopped. Use Step or Run to continue"

I checked the reference in the CPU window --------- 7c90eddc poits to line "push ebx"

I fund code that sugests that to use function "push", <queue> has to be included.

What I cannot workout is at what point in my code "push" is called.

[chrisname]

"push" is assembly, so it's not in "your" code as such.
It's compiler generated code to push the value of %ebx (which is a register; tiny (2 byte) piece of storage space on the CPU (on the die itself, so it's faster to access even than Ln Cache) http://en.wikipedia.org/wiki/Processor_register ) onto a stack of some sort.

Example:

push %eax # Push eax onto the stack
pop %eax # Remove eax from the stack 

[Peter1234]

I have compiled the unaltered code outside Borland Builder without problem.