I have problem converting String^ containing 8 bytes as characters (as ascii) to double.
I want to take those 8 characters and convert them binary to double.
What would you recommend to do this conversion in C++/cli?
I was trying to use Marshal::Copy, Double::TryParse, etc.
Maybe I use wrong specifications of parameters, but I really lost my last hopes.
There must be something easy to do this conversion.
Thanks.
Well, the bad news is that the System.String class uses only Unicode encoding internally.
So if you give it bytes it will map them to its internal encoding hiding the original value.
The good news is that you can play with the System.Text.Encoding class to retrieve 8bits values corresponding to the unicode characters.
Here is a sample :
#include <iostream>
using namespace System;
using namespace System::Text;
int main()
{
int n = 123456;
double d = 123.456;
std::cout << n << std::endl;
std::cout << d << std::endl;
char* n_as_bytes = (char*)&n;
char* d_as_bytes = (char*)&d;
String^ n_as_string = gcnew String(n_as_bytes, 0, sizeof(n));
String^ d_as_string = gcnew String(d_as_bytes, 0, sizeof(d));
Encoding^ ascii = Encoding::GetEncoding("iso-8859-1");
array<Byte>^ n_as_array = ascii->GetBytes(n_as_string);
array<Byte>^ d_as_array = ascii->GetBytes(d_as_string);
cli::pin_ptr<unsigned char> pin_ptr_n = &n_as_array[0];
cli::pin_ptr<unsigned char> pin_ptr_d = &d_as_array[0];
unsigned char* ptr_n = pin_ptr_n;
unsigned char* ptr_d = pin_ptr_d;
int n_out = *(int*)ptr_n;
double d_out = *(double*)ptr_d;
std::cout << n_out << std::endl;
std::cout << d_out << std::endl;
return 0;
}
This should give you :
123456
123.456
123456
123.456
Not sure it is completely safe, but trying it in your context should be a good start to ensure it is viable. :)
Related
Example
For example:
string MyString = "Normal\tString";
cout << MyString << endl;
produces the following: "Normal String"
Appending the raw string modifier to the string like so:
string MyString = R"(Normal\tString)";
cout << MyString << endl;
produces the following: "Normal\tString"
The Question
Is there a way to append the raw string modifier to a variable containing a string in order to print the raw form of the string contained within the variable?
string TestString = "Test\tString";
cout << R(TestString) << endl;
So you get: "Test\tString"
Is there a way to append the raw string modifier to a variable containing a string in order to print the raw form of the string contained within the variable?
No.
However, you can write a function that substitutes the characters that are defined by escape sequences by an appropriate string, i.e. replace the character '\t' by the string "\\t".
Sample program:
#include <iostream>
#include <string>
// Performs only one substitution of \t.
// Needs to be updated to do it for all occurrences of \t and
// all other escape sequences that can be found in raw strings.
std::string toRawString(std::string const& in)
{
std::string ret = in;
auto p = ret.find('\t');
if ( p != ret.npos )
{
ret.replace(p, 1, "\\t");
}
return ret;
}
int main()
{
std::string TestString = "Test\tString";
std::cout << toRawString(TestString) << std::endl;
}
Output:
Test\tString
This question is tagged as C++11, in which case rolling your own conversion function is probably the best call.
However, if you have a C++14 compiler, you can use the std::quoted stream manipulator:
#include <iostream>
#include <iomanip>
int main() {
string s = "Hello\tWorld!";
std::cout << std::quoted(s) << std::endl; // Prints "Hello\tWorld!"
}
Kind of. This works but it's not a pretty solution:
std::string strToInsert = " insert this "
std::string myRawString = R"(
raw string raw string raw string
raw string raw string raw string
)"; myRawString += strToInsert; myRawString += R"(raw string
raw string raw string raw string
)";
I have trouble with playing audio data after they have been manipulated.
The only API I use is the alsa lib API on Linux (Ubuntu) in C.
I get the data from a 16 bits integer wave file in a unsigned char array (called buffer1) using read() and buffer1 can be played properly. I want the data to be passed to another unsigned char array (called buffer2) of the same size. If I just make a loop with buffer2[i] = buffer1[i], it works : buffer2 can be played properly. But in order to manipulate the data, I convert it to a float array then back to unsigned char (Until now I do not manipulate the audio data; I just convert them to float then back to unsigned char to test how it works). But now buffer2 does not make sound although all of its values are strictly identical to the values of buffer1 (I made a printf of many values of buffer1 and buffer2; they are all identical) ... All I did is casting from unsigned to float and vice versa...
Please any idea of what's wrong?
Victor
The values in buffer1 and buffer2 cannot be identical or it would work. Perhaps the formatting that you use in your printf command is masking the differences (%i, %f etc.). Rather than use printf, try setting a breakpoint and looking at the values using your debugger. This might help reveal what is actually going wrong.
EDIT:
Given your comments about how you perform the cast, I think that I can now help. The raw data coming in is of type unsigned char. On most platforms, this will be an integer value between 0 and 255. You want to convert this value to a float to do your manipulation. To make the data meaningful as a floating point type for any manipulation, you want to scale this range between +/- 1.0. This is what the "scale" variable is for in the following code.
#include <iostream>
#include <math.h>
int main()
{
const int BUFFER_LEN = 6;
const unsigned char channelDataIN[] = {0,255, 1, 254, 2, 253};
unsigned char channelDataOUT[BUFFER_LEN];
float channelDataF[BUFFER_LEN];
std::cout.precision(5);
float scale = powf(2.f, 8.f*sizeof(unsigned char) ) - 1.f;
for (int mm = 0; mm < BUFFER_LEN; ++mm)
{
std::cout << "Original = " << (int)channelDataIN[mm] << std::endl;
channelDataF[mm] = (float)(channelDataIN[mm]) * 2.f/scale - 1.f; //Float cast
std::cout << "Float conversion = " << channelDataF[mm] << std::endl;
channelDataOUT[mm] = (unsigned char) ceil( ( 1.f+channelDataF[mm] ) * scale/2.f );
std::cout << "Recovered = " << (int)channelDataOUT[mm] << std::endl;
if (channelDataIN[mm] == channelDataOUT[mm])
std::cout << "The output precisely equals the input" << std::endl << std::endl;
else
std::cout << "The output != input" << std::endl << std::endl;
}
return 0;
}
The output array of unsigned chars after converting the values back is identical to the input array. This is the output from the code . . .
Original = 0
Float conversion = -1
Recovered = 0
The output precisely equals the input
Original = 255
Float conversion = 1
Recovered = 255
The output precisely equals the input
Original = 1
Float conversion = -0.99216
Recovered = 1
The output precisely equals the input
Original = 254
Float conversion = 0.99216
Recovered = 254
The output precisely equals the input
Original = 2
Float conversion = -0.98431
Recovered = 2
The output precisely equals the input
Original = 253
Float conversion = 0.98431
Recovered = 253
The output precisely equals the input
HI,
How to do Bitwise AND(&) on CString values in MFC(VC++)?
Example :
CString NASServerIP = "172.24.15.25";
CString SystemIP = " 142.25.24.85";
CString strSubnetMask = "255.255.255.0";
int result1 = NASServerIP & strSubnetMask;
int result2 = SystemIP & strSubnetMask;
if(result1==result2)
{
cout << "Both in Same network";
}
else
{
cout << "not in same network";
}
How i can do bitwise AND on CString values ?
Its giving error as "'CString' does not define this operator or a conversion to a type acceptable to the predefined operator"
You don't. Peforming a bitwise-AND on two strings doesn't make a lot of sense. You need to obtain binary representations of the IP address strings, then you can perform whatever bitwise operations on them. This can be easily done by first obtaining a const char* from a CString then passing it to the inet_addr() function.
A (simple) example based on your code snippet.
CString NASServerIP = "172.24.15.25";
CString SystemIP = " 142.25.24.85";
CString strSubnetMask = "255.255.255.0";
// CStrings can be casted into LPCSTRs (assuming the CStrings are not Unicode)
unsigned long NASServerIPBin = inet_addr((LPCSTR)NASServerIP);
unsigned long SystemIPBin = inet_addr((LPCSTR)SystemIP);
unsigned long strSubnetMaskBin = inet_addr((LPCSTR)strSubnetMask);
// Now, do whatever is needed on the unsigned longs.
int result1 = NASServerIPBin & strSubnetMaskBin;
int result2 = SystemIPBin & strSubnetMaskBin;
if(result1==result2)
{
cout << "Both in Same network";
}
else
{
cout << "Not in same network";
}
The bytes in the unsigned longs are "reversed" from the string representation. For example, if your IP address string is 192.168.1.1, the resulting binary from inet_addr would be 0x0101a8c0, where:
0x01 = 1
0x01 = 1
0xa8 = 168
0xc0 = 192
This shouldn't affect your bitwise operations, however.
You of course need to include the WinSock header (#include <windows.h> is usually sufficient, since it includes winsock.h) and link against the WinSock library (wsock32.lib if you're including winsock.h).
I have an array of a large structure that I am trying to output to hard drive. I seem to be able to write to hard drive just fine (though it's difficult to verify by looking at the binary data), however when I try to read it back, I always end up with a garbled mess. Any ideas what I'm doing wrong?
here's the structure configuration:
class xyz
{
public:
double x, y, z;
};
class trianglePackage
{
public:
int score;
int position;
xyz contactCoordinates;
xyz normalVector;
xyz locatorOffset;
};
class quadanglesOutput
{
public:
int locator1position, locator2position, locator3position, locator4position;
xyz centroid;
int surfaceAreaScore;
int centroidDifferance1Score;
int centroidDifferance2Score;
int minDistance1Score;
int minDistance2Score;
int totalLocatorScore;
int totalHullScore;
int totalScore;
double surfaceArea;
double centroidDifferance1;
double centroidDifferance2;
double minDistance1;
double minDistance2;
int hull;
trianglePackage locator1, locator2, locator3, locator4;
};
and here are the read/write functions I'm using:
void outputQuadangleOutput(quadanglesOutput* output, string description, param parameters)
{
string outputName = parameters.fileName + " " + description + ".bin";
cout << "Output " << outputName.c_str() << "...";
ofstream output2;
output2.open(outputName.c_str());
output2.write(reinterpret_cast<char*>(output), streamsize(parameters.topXlist * sizeof(quadanglesOutput)));
output2.close();
cout << "done" << endl;
}
void readIn(quadanglesOutput* pointer, param parameters, string description)
{
string fileName = parameters.fileName + " " + description + ".bin";
cout << "openining " << fileName << "...";
ifstream readFile;
readFile.open(fileName.c_str());
readFile.read(reinterpret_cast<char*>(pointer), (parameters.topXlist * sizeof(quadanglesOutput)));
readFile.close();
cout << "done" << endl;
}
Typically the arrays of structures are about 100 in length, but usually only about the first 25 read back correctly, everything else is default uninitialized data.
I'm 99% sure that it's something wrong with my code, however is there a possibility it has something to do with four byte alignment?
Thanks.
It may be an issue with byte alignment, use pragma.
try wrap classes around with
#PRAGMA PACK PUSH(1)
....
#PRAGMA PACK POP
or
#PRAGMA PACK(1)
struct{
..
}
Try those as well:
Force binary flag for the stream.
ios_base::binary
readFile.open(fileName.c_str(), ios_base::binary);
Try to flush the the stream.
stream.write(...)
stream.flush()
//i know that close() should flush it.
UPDATE:
Everything works for me:
#include <iostream>
#include <fstream>
#include <string>
#include <stdlib.h>
using namespace std;
#pragma pack(1)
class xyz
{
public:
double x, y, z;
};
#pragma pack(1)
class trianglePackage
{
public:
int score;
int position;
xyz contactCoordinates;
xyz normalVector;
xyz locatorOffset;
};
#pragma pack(1)
class quadanglesOutput
{
public:
int locator1position, locator2position, locator3position, locator4position;
xyz centroid;
int surfaceAreaScore;
int centroidDifferance1Score;
int centroidDifferance2Score;
int minDistance1Score;
int minDistance2Score;
int totalLocatorScore;
int totalHullScore;
int totalScore;
double surfaceArea;
double centroidDifferance1;
double centroidDifferance2;
double minDistance1;
double minDistance2;
int hull;
trianglePackage locator1, locator2, locator3, locator4;
};
class param
{
public:
string fileName;
int topXlist;
};
void outputQuadangleOutput(quadanglesOutput* output, string description, param parameters)
{
string outputName = parameters.fileName + " " + description + ".bin";
cout << "Output " << outputName.c_str() << "...";
ofstream output2;
output2.open(outputName.c_str());
output2.write(reinterpret_cast<char*>(output), streamsize(parameters.topXlist * sizeof(quadanglesOutput)));
output2.close();
cout << "done" << endl;
}
void readIn(quadanglesOutput* pointer, param parameters, string description)
{
string fileName = parameters.fileName + " " + description + ".bin";
cout << "openining " << fileName << "...";
ifstream readFile;
readFile.open(fileName.c_str());
readFile.read(reinterpret_cast<char*>(pointer), (parameters.topXlist * sizeof(quadanglesOutput)));
readFile.close();
cout << "done" << endl;
}
int main(int argc, char *argv[])
{
quadanglesOutput a = {0};
cout<<"total score:"<<a.totalScore<<endl;
cout<<"locator position:"<<a.totalScore<<endl;
cout<<"locator position:"<<a.locator1.position<<endl;
cout<<"locator position:"<<a.locator2.normalVector.y <<endl;
cout<<"sizeof quadangsomething:"<<sizeof(quadanglesOutput)<<endl;
a.totalScore=1;
a.locator1.position=333445;
a.locator2.normalVector.y = 999.3224;
cout<<"total score:"<<a.totalScore<<endl;
cout<<"locator position:"<<a.locator1.position<<endl;
cout<<"locator position:"<<a.locator2.normalVector.y <<endl;
param p = {"C:/", 1};
outputQuadangleOutput(&a, "file1", p);
quadanglesOutput *b = new quadanglesOutput();
readIn(b, p, "file1");
cout<<"new total score:"<<b->totalScore<<endl;
cout<<"new locator position:"<<b->locator1.position<<endl;
cout<<"new locator position:"<<b->locator2.normalVector.y <<endl;
delete b;
string asdf;
cin>>asdf;
};
OUTPUT:
total score:0
locator position:0
locator2.normalVector.y :0
sizeof quadangsomething:436
total score:1
locator position:333445
locator2.normalVector.y :999.322
Output C:/ file1.bin...done
openining C:/ file1.bin...done
new total score:1
new locator position:333445
new locator2.normalVector.y :999.322
without pragma it's still correct but you can see the difference in size:
sizeof quadangsomething:440
But packing it is good when sending structures over network.
Because here system alligns it always in the same fashion.
I am a beginner with C++. I have a new project at work where I have to learn it, so I'm trying some things just to test my understanding. For this problem, I'm trying to read a file and then print it on screen. Super simple, just trying to get good at it and understand the functions that I'm using. I copied some text from a MS Word document into a notepad (*.txt) file, and I'm trying to read this *.txt file. All of the text in the word document is bolded, but other than that there are no 'unusual' characters. Everything prints out on the screen as it appears in the document except the bolded " - " symbol. This character is printed as the "u" with a hat character ("so called extended ASCII" code 150). I try to print out the integer value of this character in my array (which should be 150) but I get -106. I realize this signed integer has the same bits as the unsigned integer 150. My question is how to get the output to say 150? Here's my code:
#include <iostream>
#include <fstream>
using namespace std;
int main() {
unsigned char* input1;
int input1size = 57;
ifstream file("hello_world2.txt",ios::binary | ios::ate);
if (file.is_open()){
int size;
size = (int) file.tellg();
cout <<"This file is " << size << " bytes." << endl;
file.seekg(0,ios::beg);
input1 = new unsigned char[input1size];
file.read(input1, input1size);
cout << "The first " << input1size <<" characters of this file are:" << endl<<endl;
for (int i=0; i<input1size; i++) {
cout << input1[i];
}
cout<<endl;
}
else {
cout <<"Unable to open file" << endl;
int paus;
cin>>paus;
return 0;
}
file.close();
int charcheck = 25;
int a=0;
int a1=0;
int a2=0;
unsigned int a3=0;
unsigned short int a4=0;
short int a5=0;
a = input1[charcheck];
a1 = input1[charcheck-1];
a2 = input1[charcheck+1];
a3 = input1[charcheck];
a4 = input1[charcheck];
a5 = input1[charcheck];
cout <<endl<<"ASCII code for char in input1[" << charcheck-1 <<"] is: " << a1 << endl;
cout <<endl<<"ASCII code for char in input1[" << charcheck <<"] is: " << a << endl;
cout <<endl<<"ASCII code for char in input1[" << charcheck+1 <<"] is: " << a2 << endl;
cout <<endl<<"ASCII code for char in input1[" << charcheck <<"] as unsigned int: " << a3 << endl;
cout <<endl<<"ASCII code for char in input1[" << charcheck <<"] as unsigned short int: " << a4 << endl;
cout <<endl<<"ASCII code for char in input1[" << charcheck <<"] as short int: " << a5 << endl;
int paus;
cin>>paus;
return 0;
}
Output for all this looks like:
This file is 80 bytes.
The first 57 characters of this file are:
STATUS REPORT
PERIOD 01 u 31 JUL 09
TASK 310: APPLIC
ASCII code for char in input1[24] is: 32
ASCII code for char in input1[25] is: -106
ASCII code for char in input1[26] is: 32
ASCII code for char in input1[25] as unsigned int: 4294967190
ASCII code for char in input1[25] as unsigned short int: 65430
ASCII code for char in input1[25] as short int: -106
So it appears "int a" is always read as signed. When I try to make "a" unsigned, it turns all the bits left of the eight bits for the char to 1's. Why is this? Sorry for the length of the question, just trying to be detailed. Thanks!
What you're dealing with is the sign-extension that takes place when the char is promoted to int when you assign it to one of your a? variables.
All the higher order bits must be set to 1 to keep it the same negative value as was in the smaller storage of the char.