Re: Black magic when using fopen!?

A somewhat refined / improved version of the facilities suggested so
far by other posters, used to trim strings at the NULL character and
to inspect them, in general:

-------
#include <iostream>
#include <string>
#include <sstream>
#include <limits>
#include <iomanip>

void trim_c_str(std::string* str) {
    size_t pos = str->find('\0');
    if (pos != std::string::npos) str->erase(pos);
}

void dump_as_unsigned(std::ostream& os,
                      const std::string& str,
                      size_t w = 0,
                      const std::string& lead_sep = " ") {
    for (size_t i = 0, e = str.size(); i < e; ++i) {
        os << lead_sep << std::setw(w) << unsigned(str[i]);
    }
    os << std::endl;
}

void dump_chars(std::ostream& os, const std::string& str, size_t
spaces = 0) {
    if (spaces) {
        for (size_t i = 0, e = str.size(); i < e; ++i) {
            os << std::string(spaces, ' ') << str[i];
        }
    } else {
        os << str;
    }
    os << std::endl;
}

std::string string_details(const std::string& str) {
    static std::ostringstream oss;
    static size_t w = 0;

    if (!w) {
        oss << std::hex << unsigned(std::numeric_limits<char>::max());
        oss << std::setfill('0') << std::uppercase;
        w = oss.str().size();
    }

    oss.str("");
    oss << "---" << std::endl;
    oss << "As string:" << std::endl;
    oss << " \"" << str << "\", ";
    oss << str.size() << " chars" << std::endl;

    dump_chars(oss, str, w);
    dump_as_unsigned(oss, str, w);

    std::string c_str = str.c_str();

    if (c_str != str) {
        oss << std::endl;
        oss << "As c_str():" << std::endl;
        oss << " \"" << c_str << "\", ";
        oss << c_str.size() << " chars" << std::endl;

        dump_chars(oss, c_str, w);
        dump_as_unsigned(oss, c_str, w);

    } else {
        oss << "[ string == c_str(), no NULL characters ]";
        oss << std::endl;
    }
    oss << "---" << std::endl;
    return oss.str();
}

int main() {

    std::string s = std::string("Here ->") + '\0' + "<- is NULL";

    std::cout << "Before trimming:" << std::endl;
    std::cout << string_details(s) << std::endl;

    trim_c_str(&s);

    std::cout << "After trimming:" << std::endl;
    std::cout << string_details(s) << std::endl;
}
-------

Output:

-------
Before trimming:
---
As string:
 "Here -> <- is NULL", 12 chars
  H e r e - > < - i s N U L L
 48 65 72 65 20 2D 3E 00 3C 2D 20 69 73 20 4E 55 4C 4C

As c_str():
 "Here ->", 7 chars
  H e r e - >
 48 65 72 65 20 2D 3E
---

After trimming:
---
As string:
 "Here ->", 7 chars
  H e r e - >
 48 65 72 65 20 2D 3E
[ string == c_str(), no NULL characters ]
---
-------

[ posted for portability sake, too ]

--
 Francesco S. Carta, http://fscode.altervista.org
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