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converting string to byte in c++

This is a discussion on converting string to byte in c++ within the C++ Programming forums, part of the General Programming Boards category; is there any way to convert string to byte in c++ just like the getbytes() in java??...

  1. #1
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    converting string to byte in c++

    is there any way to convert string to byte in c++ just like the getbytes() in java??

  2. #2
    and the hat of wrongness Salem's Avatar
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    Like using the [ ] operator perhaps?
    Code:
    #include <iostream>
    #include <string>
    #include <iomanip>
    int main ( ) {
        std::string foo = "hello";
        std::cout << "Letter=" << foo[0] << std::endl;
    }
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  3. #3
    a guy with long hair Xupicor's Avatar
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    Well, getBytes() returns an array of bytes, so I think the closest to that would be using string::c_str() to get a pointer and copy the characters to a new char array (or copy them using operator[]).

    Code:
    std::string str = "hello world";
    char* cstr = new char [str.size() + 1];
    std::strcpy(cstr, str.c_str());
    //...
    delete [] cstr;
    Or even better, use a vector like Elysia suggested below.
    Last edited by Xupicor; 06-13-2011 at 09:52 AM.

  4. #4
    C++まいる!Cをこわせ! Elysia's Avatar
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    Don't forget to delete that!
    A better approach:
    Code:
    std::string str = "Hello World";
    std::vector<char> bytes(str.begin(), str.end());
    Xupicor likes this.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  5. #5
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    thanks for the help and sorry for the late reply but i was thinking of a little something like this one

    Code:
    public class TestByte
    {    
    	public static void main(String[] argv) {
     
    		    String example = "This is an example";
    		    byte[] bytes = example.getBytes();
     
    		    System.out.println("Text : " + example);
    		    System.out.println("Text [Byte Format] : " + bytes);
     
     
    	}
    }
    The output is

    Text : This is an example
    Text [Byte Format] : [B@187aeca

    is this possible to do in c++?

  6. #6
    a guy with long hair Xupicor's Avatar
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    A "byte format" baffles me. You do realize that "[B@187aeca" is just a textual representation of the variable. "[B" means its an array of bytes, and the rest of it is probably an address. It's not what you'd get if you'd loop over the array and print it byte by byte.

    So, you already have "bytes" available in a string trough operator[], and if you want to have an array or a vector of bytes/chars, then just use the code above. I fear, though, that you don't quite get the whole shebang with c-strings/char arrays and std::string in the first place. In this case I think you should read trough these:
    Character Sequences - C++ Documentation
    C Strings - C Tutorial - Cprogramming.com
    Cprogramming.com - C++ Standard Library - String Class

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    thanks..not the answer i am looking for but it helps in another way..

  8. #8
    C++まいる!Cをこわせ! Elysia's Avatar
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    Then what do you want? You have your array of bytes (examples above).
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  9. #9
    Cat without Hat CornedBee's Avatar
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    A Java String is a sequence of Java chars, which are UTF-16 codepoints. getBytes() without arguments takes the platform default encoding (some Windows-xxxx codepage under Windows, UTF-8 on most Unices) and converts the Unicode sequence to that encoding, returning the resulting data as a byte array.

    A C++ std::string already is a sequence of bytes in the platform default encoding (strictly speaking, it's a sequence of bytes whose interpretation is up to you, but this is the way most library functions treat it), so your question makes no sense. There's nothing to convert.
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    Perhaps the best question is, what are you trying to do?
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