Refer to a std::string as a char*

Question

I would like to refer (write) to a std::string like I would to a string literal (char*). This is what I'm trying to do:

  std::string File::readAll(){
    std::string ret;
    ret.reserve(this->size+1);
    fseek(file, 0, SEEK_SET);

    fread((char*)ret.c_str(), size, 1, this->file);
    ret.append("\0");

    return ret;
  }

The string remains empty when I do this. How can I make this work?

Reread the docs on reserve vs resize, and consider which characters exist at which times. — Mooing Duck, Feb 28 '21 at 22:06
@1201 it's also unnecessary since std::string always implicitly has a null character at the end. — Ayxan Haqverdili, Feb 28 '21 at 22:18
Related: [How do I read an entire file into a std::string in C++?](https://stackoverflow.com/questions/116038/) — Remy Lebeau, Mar 01 '21 at 07:38

Ayxan Haqverdili · Accepted Answer · 2021-03-01T07:51:06.540

4

Replace reserve with resize and then use .data() (or &ret[0] pre C++17) instead of .c_str().

edited Mar 01 '21 at 07:51

answered Feb 28 '21 at 22:07

Ayxan Haqverdili

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Thanks! It worked – Serket Feb 28 '21 at 22:07
1

Or, `&ret[0]` in earlier versions where `data()` doesn't exist (pre-C++11), or returns a `const char*` only (pre-C++17) – Remy Lebeau Mar 01 '21 at 07:35
@RemyLebeau Thank you for the feedback. Added that in. – Ayxan Haqverdili Mar 01 '21 at 07:51

Refer to a std::string as a char*

1 Answers1