Problem : 
For years in Fortran95, I've been reading and writing files into various directories of my choice, thus keeping our data files in an orderly fashion. However, now I am shocked to find that you can't do anything like that in C++.

Please tell me if there is a way, and give me an example.

Environment : 
Intel C++ compiler for Linux*

Resolution : 

This is not a compiler issue. You need to have suitable access rights to the file. You can take help from system administrator to get suitable access rights for the file. I am providing a sample test case that I tried at my end in FC11 box. It works without issue.

// file_rw.cpp
//

#include <fstream>
#include <iostream>
using namespace std;

int main()
{
    char str[2000] ;
    fstream fs( "/testdir/prt1.txt", ios::in ) ;

    if(!fs) {
        cout << "Cannot open input file.\n";
        return 1;
    }

    fstream ft( "/testdir/prt2.txt", ios::out | ios::in ) ;
    if(!ft) {
        cout << "Cannot open output file.\n";
        return 1;
    }

    while ( !fs.eof() )
    {
        fs.getline(str, 2000 ) ;
        ft << str << endl;
    }
    fs.close () ;
    ft.close ();
    return 0;
}

Problem : 

I was looking for "fasm-blocks" decription in "Intel C++ Compiler User & Reference Guide" (304968-022US) which seems to be the latest document with release of ICC-v11.0. The agnostic about it is "fasm-blocks" works with ICC-11.0 on Linux x86_64 but the descriptions about "fasm-blocks" is missing.

Could Intel describe it's meaning, uses, also demonstrate with an example currently and latter incorporate in it's feature forthcoming ICC documents.

Can I have Intel Assembler latest documents or it's links to download w.r.t Intel 64 on Linux x86_64 where one can understand and analyze Intel Assembly language?


Environment : 

Linux* and MacOS X*

Resolution : 


Intel C++ compiler uses gcc development environment on Linux and MAC. It supports GNU inline style assembly.

Intel C++ compiler also supports Microsoft style inline assembly format in Linux. You can use -use-msasm to tell the compiler. The -fasm-blocks is also seems to be working.

The -fasm-blocks option is provided on MAC for Microsoft style inline assembly.

These options are described in Intel C++ compiler documentation, Document number: 304968-022US. There is small description of the inline assembly implementation in Intel C++ compiler in "Inline Assembly" topic.

I am providing the code sample from the Intel C++ compiler documentation below for easy reference:

---------------------------------------- gnu style inline assembly ------------------
$ cat tstcase_gnu.cpp
// inline assembly
// tstcase_gnu.cpp

#ifdef _WIN64
#define INT64_PRINTF_FORMAT "I64"
#else
#define __int64 long long
#define INT64_PRINTF_FORMAT "L"
#endif
#include <stdio.h>
typedef struct {
__int64 lo64;
__int64 hi64;
} my_i128;
#define ADD128(out, in1, in2) \
__asm__("addq %2, %0; adcq %3, %1" :\
"=r"(out.lo64), "=r"(out.hi64) : \
"emr" (in2.lo64), "emr"(in2.hi64), \
"0" (in1.lo64), "1" (in1.hi64));
extern int main()
{
my_i128 val1, val2, result;
val1.lo64 = ~0;
val1.hi64 = 0;
val2.hi64 = 65;
ADD128(result, val1, val2);
printf("0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
val1.hi64, val1.lo64);
printf("+0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
val2.hi64, val2.lo64);
printf("------------------------------------\n");
printf("0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
result.hi64, result.lo64);
return 0;
}


---------------------------------------- Microsoft style inline assembly ------------------

$ cat tstcase_msasm.cpp
// inline assembly
// tstcase_msasm.cpp

#ifdef _WIN64
#define INT64_PRINTF_FORMAT "I64"
#else
#define __int64 long long
#define INT64_PRINTF_FORMAT "L"
#endif
#include <stdio.h>
typedef struct {
__int64 lo64;
__int64 hi64;
} my_i128;
#define ADD128(out, in1, in2) \
{ \
__asm mov rax, in1.lo64 \
__asm mov rdx, in1.hi64 \
__asm add rax, in2.lo64 \
__asm adc rdx, in2.hi64 \
__asm mov out.lo64, rax \
__asm mov out.hi64, rdx \
}

extern int main()
{
my_i128 val1, val2, result;
val1.lo64 = ~0;
val1.hi64 = 0;
val2.hi64 = 65;
ADD128(result, val1, val2);
printf("0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
val1.hi64, val1.lo64);
printf("+0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
val2.hi64, val2.lo64);
printf("------------------------------------\n");
printf("0x%016" INT64_PRINTF_FORMAT "x%016" INT64_PRINTF_FORMAT "x\n",
result.hi64, result.lo64);
return 0;
}

You would need -use-msasm compiler option to compile tstcase_msasm.cpp. The -fasm-blocks is also seems to be working on Linux but this is intended for MAC OS.