18.limits.stdcxx-436.cpp

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#include <assert.h>  // for assert()
#include <limits.h>  // for MB_LEN_MAX
 
// tell Compaq C++ we need the declaration of the POSIX popen() function
// that's guarded (not declared) in the compiler's pure C++ libc headers
#undef __PURE_CNAME
#include <stdio.h>   // for popen(), fscanf(), pclose(), ...
 
#ifdef _WIN32
#  define popen  _popen
#  define pclose _pclose
#endif  // _WIN32
 
int main ()
{
    // assumes getconf is in the path. on most unix systems it is in
    // '/usr/bin' and it doesn't exist on most win32 configurations,
    // yet somehow this appears to work on windows, but not sure how.
 
    FILE* f = popen ("getconf MB_LEN_MAX", "r");
    if (f) {
 
        int mb_len_max = -1;
 
        const bool failed = fscanf (f, "%d", &mb_len_max) != 1;
 
        pclose (f);
 
        // if getconf isn't available, or getconf doesn't know the limit
        // the scan will fail, so we must handle both situations.
        assert (failed || MB_LEN_MAX == mb_len_max);
    }
 
    return 0;
}