C++ :: Copying Two Unsigned Char Into Unsigned Char
Mar 30, 2014
unsigned char key[32];
139 unsigned char rfseed[32];
173 f = fopen("/dev/urandom","rb");
174 fread(key,1,32,f);
175 fread(rfseed,1,32,f);
I am having problems copying outputs of the above code into other unsigned char other[32]. I need to keep the output of dev/urandom for backup. But, when I try to assign the values by memcpy(other, key, 32), the values do not match. The same problem happens by assigning values index by index in a loop.
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Apr 23, 2013
How do I print an unsigned char in c++? E.g.
unsigned char a[100] = "acdef";
wprintf(L"a is %u
", a);
wcout << "a is " << a << endl;
gives
a is 2880488
a is 002BF3E8
and not
a is acdef
a is acdef
??
what is the difference between unsigned char and char?
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Oct 4, 2014
How do I convert a variable of type unsigned char to string.
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May 7, 2013
I am having some trouble performing this. I am not sure, if my unsigned char arrays are null terminated, but I don't think so. Here is my code: They are supposed to be byte arrays of size 16.
int setkey(unsigned char* ky) {
printf("INSIDE POLY-DEL ... key byte array passed in HEX:
");
int i;
for (i = 0; i < (int)16; i++)
[Code] .....
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Mar 10, 2014
How do you use char instead of unsigned to calculate numbers? This is using char only and nothing else.
Step 1: I ask the user to enter a number.
Step 2: User enters a number.
Step 3: Number user entered is going to be that number squared or cubed or w/e.
For example;
"Enter a number: " 3
" Number you entered multiplied four times: " 81 (Since (3)*(3)*(3)*(3) = 81)
Another example;
"Enter a number: " 5
" Number you entered multiplied four times: " 625 (Since (5)*(5)*(5)*(5) = 625)
Code:
Char num;
cout << "Enter a number";
cin >> num;
cout << "Number you entered multiplied four times: " << (num)*(num)*(num)*(num) << endl;
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Nov 16, 2014
i wish to generate all possible key combinations ranging:
HEX: "0F FF FF FF FF FF FF FF" TO HEX: FF FF FF FF FF FF FF FF
i also test each key after incrementing by 1, for test i want the key to be a an unsigned char[8]
key start rang and end range can be initialize/declare in any format.
Problem is if :
unsigned char key[] = {0x0F,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
then i can not increment this key by +1 , though if i initialize this key in decimal as:
unsigned long long key = 1152921504606846975;
then i can increment the key in for loop by key++ but then i cant convert it back into unsigned char array
i want to achieve something like this :
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
unsigned char key[] = {0x0F,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
int main()
{
[code]...
In my programer i also have function that test each key but key has to be unsigned char...
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Dec 2, 2013
I came across some code and it's not clear why it is casting an unsigned char * to another pointer type only to free it right after. Here are the relevant structures:
Code:
struct _Edje_Message {
Edje *edje;
Edje_Queue queue;
Edje_Message_Type type;
int id;
unsigned char *msg;
[Code] .....
As you can see, _Edge_Message has a *msg field, but in the function below, they cast it to the other two structure types inside the case blocks of the switch statement only to free it. What is the point or advantage of doing this?
Code:
void
_edje_message_free(Edje_Message *em) {
if (em->msg) {
int i;
switch (em->type) {
[Code] ......
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Mar 24, 2015
I have the following code, but it crashes on the "data = " line...
Code:
void Test(string& data) {
unsigned char* msg = (unsigned char*)malloc(MAX_LENGTH));
...
data = string(reinterpret_cast<const char*>(msg), MAX_LENGTH);
}
I know I could just return string, but what is wrong with this code that is making it crash?
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Apr 9, 2015
Got something like the following. A button that read characters from a thrid party tool and sends it to a listbox. But the contant is not readable.
Code:
void dlg::sendtolistbox() {
unsigned char buf[250];
thirdparty.GetData(buf, len);
Sendmessage(hndl, listboxupdate,0 , (LPARAM)buf);
}
void Mydlg::UpdateListBox(wparam a,laparm b) {
m_listbox.AddString((LPCTSTR)b);
}
The characters show up in the list box as short unreadable characters. like it is chopped.
If i change to : Sendmessage(hndl, listboxupdate,0 , (LPARAM)&buf[15]);
Then I can see readable valid strings of up to 50 characters and then empty unreadable characters afterwards. I tried all kinds of things , including using CString, still did not work.
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Jan 13, 2015
I have an embedded microcontroller system communicating with a similar system by radio. The api for the radio requires data to be transmitted as an unsigned char array. It will always transmit a positive integer in the range 0 to 255.When I receive the data I am having difficult in extracting this positive integer.
Code:
unsigned char rxData[4]={'1','2','3',''};
int inVal=0;
//want to assign inVal whatever number was transmitted
E.g. 123
I've been at this for a week and have tried at least 10 different approaches including the use of the atoi(), copying the absolute value of each element of rxData into another char array, reinterpret_cast, and others.
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Mar 5, 2014
I need to convert the bit representation of an unsigned char into a string.
so like 254 would be "11111111"
I'm having some trouble where no matter what number I try to convert I get 01111111.
string bin2string(unsigned char N) {
string sN(8,'0');
unsigned char X;
unsigned char Y = 0;
for(int i = 0; i < 8; i++){
[Code] ....
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Dec 1, 2014
I need fastest method to reverse order of bytes in my char array.
For example i have:
unsigned char buf[8];
// consider data stored in buf is 88 77 66 55 44 33 22 11
// how to reverse it to: 11 22 33 44 55 66 77 88
// currently i can do it by equal assignment , i make another buf like:
unsigned char buf_ok[8];
[Code] ....
// This does reverse the bytes as i want but its very slow , i am looking for fast method ..
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Aug 3, 2014
I'm having a pretty weird problem. I've created an unsigned char array for an image buffer:
buffer_rgb = new unsigned char[_w * _h * 3];
memset(buffer_rgb, 0x0, sizeof(unsigned char)* _w * _h * 3);
And I add pixel color values to it like so:
buffer_rgb[i] = ((unsigned char)(col[0] * 255));
buffer_rgb[i + 1] = ((unsigned char)(col[1] * 255));
buffer_rgb[i + 2] = ((unsigned char)(col[2] * 255));
Where col is a 'vec4' struct with a double[4] with values between 0 and 1 (this is checked and clamped elsewhere, and the output is safely within bounds). This is basically used to store rgb and intensity values.
Now, when I add a constant integer as a pixel value, i.e.:
buffer_rgb[i] = ((unsigned char)255;
Everything works as it should. However, when I use the above code, where col is different for every sample sent to the buffer, the resulting image becomes skewed in a weird way, as if the buffer writing is becoming offset as it goes.
These two images illustrate the problem:
tomsvilans.com/temp/140803_render_skew.png
tomsvilans.com/temp/140803_render_noskew.png
You can see in the 'noskew' image all pixels are the same value, from just using an unchanging int to set them. It seems to work with any value between 0-255 but fails only when this value is pulled from my changing col array.
Whole function is here:
// adds sample to pixel. coordinates must be between (-1,1)
void Frame::addSample(vec4 col, double contrib, double x, double y) {
if (x < -1 || x >= 1 || y < -_aaspect || y >= _aaspect) {
[Code] .....
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Jan 10, 2014
I have a bitmap header information in the struct
typedef struct tagBITMAPINFO {
BITMAPINFOHEADER bmiHeader;
RGBQUAD bmiColors[1];
} BITMAPINFO
The total size of this is 1080.
Now i want to convert this into a unsigned char pointer.
unsigned char * pBMPHeaderData;
I already got the raw image data in another unsigned char buffer.
unsigned char* pRawBMPData;
Now i want to make a complete BMP image by adding the header info and raw data into a new unsigned char pointer. For this i need to convert the BITMAPINFO struct into a unsigned char *
So the new buffer will be,
unsigned char * pCompleteBMPIMageData = pBMPHeaderData + pRawBMPData;
how to do this?
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Apr 3, 2014
How can i write a function that will read an "unsigned integer" into a variable of type "unsigned short int"? i can not use cin >> inside the function.. so i am looking for atleast a hint!
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May 10, 2013
I would like to convert a float or double variable into unsigned char variable and back.
float number_float = 23.453f;
unsigned char* number_char = (unsigned char*)malloc(sizeof(float));
number_char = reinterpret_cast<unsigned char*> (&number_float);
float* number_float_0 = reinterpret_cast<float*>(&number_char);
I am not getting the same value back.. why?
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Oct 25, 2013
I am trying to assign the integer value to unsigned char array. But it is not storing the integer values. It prints the ascii values. Here the code snippet
Code: uchar uc[100];
for(i=0;i<100;i++)
{
uc[i] = i;
}
The values which are stored in uc[] is ascii values.I need the integer values to be stored in uc[]. I tried to do it with sprintf. but the output is not as expected. if I print the uc[i] it should diplay the value as 0,1,2....99.
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Mar 2, 2012
I have the following code which attempts to assign a u_int8 array of 256 to an unsigned char[256]:
Code:
unsigned char testData[256]=pSample->data;
I get the compilation error:
error C2440: 'initializing' : cannot convert from 'const uint8_t [256]' to 'unsigned char [256]'
What is the safe way to cast or convert here?
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Apr 6, 2014
This program works as expected:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct {
unsigned long long int address;
float current;
unsigned char pressure_units;
}
[code]....
But I don't like how I had to use malloc and free. Is there a different way to accomplish copying the string into a char pointer without resorting to dynamic memory allocation?
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Mar 25, 2014
Is it really needed to specify 0 as an unsigned integer? I mean 0 is always 0 regardless it's signed or not, no? In the below example is the 0U really needed?
#include <stdio.h>
unsigned invert(unsigned x, int p, int n) {
return x ^ (~(~0U << n) << p);
}
int main(void) {
[Code]...
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May 15, 2014
Consider this piece of code from the following website: [URL] .....
Code:
unsigned intx = 50;
x += (x << 2) + 1;
The website above says the following about the code:
Although this is a valid manipulation, the result of the shift depends on the underlying representation of the integer type and is consequently implementation-defined.
How exactly would a legal left shift operation on an unsigned integer result in implementation-defined behaviour?
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Nov 10, 2014
I need to convert a string IP to an unsigned int (uint32), but however solutions I've found elsewhere have not worked (such as `atoi`).
When using `(uint32)"54.171.82.217 ";` : [URL] ....
When using `atoi("54.171.82.217");`: [URL] .....
How can I correctly convert the string version of the IP to the uint32 type?
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Jan 26, 2014
I'm confused about the actual value of 8 bytes for unsigned integers.
The below code suggests the value is 13217906525252912201:
#include <stdio.h>
#include <inttypes.h>
typedef uint64_t byte_int_t;
int main(void){
byte_int_t t;
printf("%" PRIu64 "
", t);
}
./runprogram
13217906525252912201
However, when I use a calculator, I get a different value: 2^64= 1.8446744e+19
So I was wondering is this really 8 bytes? So I try below test and it produces 8, as expected:
#include <stdio.h>
#include <inttypes.h>
typedef uint64_t byte_int_t;
int main(void) {
byte_int_t t;
printf("%u
", sizeof(t));
return 0;
}
So why does C and my calculator provide two different results?
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Aug 8, 2013
I have a double variable and depending on certain conditions I need to set certain bits of an unsigned short Variable. For example, if double var is odd I need to set the 15th bit of the unsigned short variable.
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Jan 15, 2013
when you convert 1.7 to unsigned int, it becomes 1 or 2?
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Oct 12, 2012
I've sometimes encountered unexpected runtime issues caused by unsigned values being decremented below zero.
Example 1: "unsigned_value += negative_integer_value;"
Example 2: "for( size_t i = size - 1; i >= 0; --i )"
My compiler doesn't provide any compile-time or run-time warnings.
As far as I know, it's not possible to overload operators of primitive data types to check if the unsigned value is decremented below zero.
Any clever strategy to trace such cases at debug runtime, without having to add asserts all over the code? It's important that it does not affect performance in release mode.
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