C++ :: How To Extract Positive Integer From Unsigned Char Array
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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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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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 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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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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Jan 16, 2015
I am trying to extract unsigned values from an input stream. I expect the extraction to fail when an invalid character is extracted. It fails correctly when I try to extract an unsigned int from "abc", but when I try to extract an unsigned in from "-1", the extraction succeeds, and the max unsigned int value is extracted (as if -1 were cast to unsigned int). I would expect the '-' to cause the extraction of an unsigned value to fail.
The code I am using is below.
#include <iostream>
#include <sstream>
#include <string>
#include <limits>
int main() {
unsigned int value = 8;
std::string negString = "-1";
[Code]...
Is this standard behavior for an istream extractor?
I am trying this in both Linux (gcc 4.4.3) and in windows with Code::Blocks (whaterver came with CB 13.12, apparently gcc 4.7.1)
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Oct 29, 2014
I was going through the following statement in a c book:
"interpreting -1 as unsigned int leads to a big +ve number"
-1 is already unsigned .... then what does the above statement mean ??
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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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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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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 25, 2013
Consider a new data type, the mikesint, which can hold 9 bits.
(a) What is the largest integer that an unsigned mikesint can hold?
(b) What is the largest positive integer that a signed mikesint can hold?
(c) What is the largest negative integer that a signed mikesint can hold?
Not sure how to determine this. I'm stuck.
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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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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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Dec 6, 2014
I need to create a stack with the container being an unsigned int. I tried to put in numbers up to four bits each and have the program read the numbers individually. This is the code I am using:
void push(int n)//item n is pushed onto the stack, throw exception on full stack {
string str="Error";
if (isFull())
throw str;
[Code] ....
When I have tested it, the program is reading the numbers as one whole number. For example, I put in the number 2, and it displays the number 2. Then I put in 2 again, but this time it displays the number 10, instead of 2 2.
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Apr 15, 2013
Looking for extended unsigned integer class, that has custom lenght?
The reason i am asking is because i need an extremely large integer number, in fact one that has no theoretical limit(or at least an extremely large one).
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Dec 28, 2013
Constructing this right aligned half pyramid? The code I had so far is right aligned and they're not in numbers
Write a program that receives one positive integer and display
_________ _ 1
________ 4 2
_______9 6 3
___16 12 8 4
25 20 15 10 5
when the user key in 5.PS: ignore the line
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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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Aug 10, 2014
You pros are once newbies like us. Hoped you might take a little time sharing your expertise. Got freaked out when our teacher gave us this activity, where she haven't taught this to us yet. So this is the activity (LOOPING) :
Write a program that accepts a positive integer. The program should be the same from the given output. Use do while to allow the user to continue or not.
OUTPUT must be:
n = 5
0
1==0
2==1==0
3==2==1==0
4==3==2==1==0
5==4==3==2==1==0
if n = 6
0
1==0
2==1==0
3==2==1==0
4==3==2==1==0
5==4==3==2==1==0
6==5==4==3==2==1==0
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Sep 17, 2013
Write a program asks the user for a positive integer value and then prints out all perfect numbers from 1 to that positive integer. I have been trying for some time, i found a way to check if its a perfect number or not but could not find a way to prints out all perfect numbers from 1 to that positive integer. I am here so far.
#include<iostream>
#include<iomanip>
using namespace std;
int main(){
int n,i=1,sum=0;
cout<<"Enter a number: ";
[Code] ....
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Feb 17, 2013
My question is are there various ways that I can approach this program. I.e. do I have to use switch statements?
/*
NumToTxt
Creates the appropriate word form of any positive integer up to 999999
*/
#include <iostream>
using namespace std;
//represents the largest array size for the user entered number
const int MAXNUMARRAY = 6;
/*represents the largest number that can be entered + 1. Used to calculate the first number used to truncate the user
entered number and to display an error message to the user that tells the user the largest number that the program will
accept. */
const int BIGGESTNUMBER = 1000000;
[Code] .....
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Jul 13, 2014
convert a positive integer code into its english name equivalent for digit. A valid code is of size between four (4) to six (6) digits inclusive. A zero is not allowed in the code.
example : if the input is 234056 the output is : INVALID CODE (PRESENCE OF ZERO)
if the input is 23456 the output is : TWO THREE FOUR FIVE SIX
if the input is 9349 the output is : NINE THREE FOUR NINE
if the input is 245 the output is : INVALID CODE (3 DIGITS)
if the input is 2344567 the output is : INVALID CODE (7 DIGITS)
step 1 : input code
step 2 : count the number of digits in the code
step 3 : if there is a zero in the code, "INVALID CODE (PRESENCE OF ZERO)" go to step 4
step 4 : if number of digits is mode or equal than 4 and less or equal than 6, go to step 5 else display the following message "INVALID CODE (<number of digits> DIGITS)
step 5 : call a function called digit_name to convert each digit into its
equivalent english name. display the result
step 6 : print the digits in reverse order
eg; if input is 13453, reverse order is 35431
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Aug 10, 2014
So this is the activity (LOOPING) :
Write a program that accepts a positive integer. The program should be the same from the given output. Use do while to allow the user to continue or not.
OUTPUT must be:
n = 5
0
1==0
2==1==0
3==2==1==0
4==3==2==1==0
5==4==3==2==1==0
if n = 6
0
1==0
2==1==0
3==2==1==0
4==3==2==1==0
5==4==3==2==1==0
6==5==4==3==2==1==0
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Oct 4, 2014
How do I convert a variable of type unsigned char to string.
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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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May 16, 2014
I know that you're allowed to use a char pointer to access any object but are you allowed to inspect a char array with a different type, say an unsigned integer without breaking the strict aliasing rule? My understanding is that it's not legal and could lead to trouble with trap representations but I just wanted to make sure.
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