How do right read file via stdio? C++

Question

I want to read file via stdio for RapidXML. I used following:

#include <iostream>
#include <rapidxml.hpp>
#include <stdio.h>
#include <Windows.h>

using namespace rapidxml;

int main(int argc, char** argv)
{
    FILE *pFile;
    pFile = fopen("D:\\ColladaFiles\\sample1.dae", "rb");
    long lSize;
    char *buffer;
    size_t result;

    //if error
    if (pFile == NULL) { fputs("File error", stderr); exit(1); }

    // obtain file size:
    fseek(pFile, 0, SEEK_END);
    lSize = ftell(pFile);
    rewind(pFile);

    // allocate memory to contain the whole file:
    buffer = (char*)malloc(sizeof(char)*lSize);
    if (buffer == NULL) { fputs("Memory error", stderr); exit(2); }

    // copy the file into the buffer:
    result = fread(buffer, 1, lSize, pFile);
    if (result != lSize) { fputs("Reading error", stderr); exit(3); }

    /* the whole file is now loaded in the memory buffer. */

    xml_document<> xdoc;
    xdoc.parse<0>(buffer);

    system("pause");
    return 0;
}

RapidXML generated an error. Because If I write buffer following:

std::cout << buffer << std::endl;

Last line is contains a following: enter image description here How do fast read a file for RapidXML?

@ScarletAmaranth You didn't get the memo? Sarcasm doesn't work on the internet. Especially not in context-less comments. So: spelling it out: this is C, compiled with a C++ compiler. — sehe, Dec 22 '13 at 15:09

score 0 · Answer 1 · answered Dec 22 '13 at 14:27

0

You missed two things:

on malloc:

buffer = (char*)malloc(sizeof(char)*lSize + 1); //place for '\0';
after fread:

buffer[lsize]='\0'; //terminate string

You can also use fgets() or std::ifsteam method getline

answered Dec 22 '13 at 14:27

SHR

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Is std::ifsteam a fast method? I mean, that a streaming methods is slower than c-methods for read. – Ivan Dec 22 '13 at 14:32
`std::ifsteam` is a class. `getline` is the method to read with spaces, you can set delimiter to 0 to read all from text file. it is more c++ then fread/fgets which are c methods. also you can use `new` instead of `malloc`, `delete` instead of `free` (by the way: you missed the free), and so on. if you want to go further, you can also read directly to std::string. – SHR Dec 22 '13 at 14:36
look here at the first answer for the best way to do it: http://stackoverflow.com/questions/2602013/read-whole-ascii-file-into-c-stdstring – SHR Dec 22 '13 at 14:40

score 0 · Answer 2 · answered Jan 08 '14 at 05:26

0

The following line expects char array with null termination character(‘\0') at the end of the array.

xdoc.parse<0>(buffer);

So add following lin after reading file, and also allocate space for that '\0’.

buffer[lSize]='\0

answered Jan 08 '14 at 05:26

dg_no_9

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score 0 · Answer 3 · edited May 23 '17 at 11:57

0

For C++ you shouldn't be reading the file that way. See this question. Read whole ASCII file into C++ std::string

Basically, Try this instead.

std::ifstream t("D:\\ColladaFiles\\sample1.dae"); 
std::stringstream buffer; 

buffer << t.rdbuf(); //read file into stringstream

xdoc.parse<0>(buffer.str().c_str()); // parse it

edited May 23 '17 at 11:57

Community

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answered Jan 10 '14 at 10:29

Roddy

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How do right read file via stdio? C++

3 Answers3