C :: Unsigned Integer Representation
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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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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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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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 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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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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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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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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Mar 10, 2014
I am using a structure , and when i am assing values i get the warning message , how do I avoid that ?
Code:
// header file
typedef struct {
unsigned _T_ipset:1;
unsigned RTCSetNewTime:1;
unsigned PassWord:1;
unsigned UserReset:1;
unsigned PCDEBUG:1;
unsigned PWRUP:1;
unsigned HostTaskShift:1;
unsigned TimeToConnMstr:1;
unsigned En_Display_Lcd:1;
}
[code]....
large integer implicitly truncated to unsigned type
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Jul 23, 2014
I am using MCC18 for use with MPLAB.
0bnnnnnnnn means a binary representation.
0x00 means a hex number representation.
What does sd001 means? signed decimal 1? if so how do I represent a -1 using this sdnnnn format?
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Mar 6, 2015
How to convert e.g. number 75 to base 4 representation? The result should be 1023. I plan to use uint32_t
x = a3.43 + a2.42 + a1.41 + a0.40 = a3.64 + a2.16 + a1.4 + a0
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Jan 24, 2015
I'm looking for something that can hold the current time, but is independent of the user adjusting the OS's time, and that can be converted to a std::string and back and that meets the requirements of LessThanComparable and EqualityComparable, I search online but I couldn't find anything suitable.
I can't use The C++ Standard Chrono Library because:
std::chrono::system_clock you can change the OS's time
std::chrono::steady_clock and std::chrono::high_resolution_clock cannot be converted to a std::string and back
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Nov 1, 2014
I'm currently trying to learn about floating point representation in depth, so I played around a bit. While doing so, I stumbled on some strange behaviour; I can't really work out what's happening...
#include <iostream>
#include <cmath>
using namespace std;
int main(){
float minVal = pow(2,-149); // set to smallest float possible
float nextCheck = ((float)((minVal/2.0f))); // divide by two
[Code] ....
Essentially what's happening is:
- I set minVal to be the smallest float that can be represented using single precision
- Dividing by 2 should yield 0 -- we're at the minimum
- Indeed, isZero2 does return true, but isZero returns false.
What's going on -- I would have thought them to be identical? Is the compiler trying to be clever, saying that dividing any number cannot possibly yield zero?
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May 3, 2014
"My Programm is crashing and i dont know why?"
#include<iostream>
using namespace std;
int arr[3];
struct edges {
int edge_data;
edges *next;
[code]....
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Jul 19, 2013
Data structure problem. I have a table of the following format:
Code:
C/R 1 2 3 4 5 6 7 ...
1 x x x
2 x
3 x
4 x
5 x x x
6
... s
So my column and row names are integer numbers if an outcome of some game for a certain column and row lable is a match then we have an x on that position. The size of the integer names for both column and row name is quite large (let us imagine that it is so large that you would need a machine with 500GB of RAM memory to hold this type of table even if x's are treated as regular char's) . In every row there is at least one x and for every column the same holds for the columns. However, the number of x's for a row or a column can be bigger then 1. How to store this table efficiently? (using as less memory as possible).
The data structure should be efficiently accessed in the column fashion that is, if i want to get all values for column 4 I should be able to do that in O(N) time where N= the number of rows.
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Jan 25, 2014
The program is supposed to convert a two digit hexadecimal number to its binary representation. My code runs without any problems but I do not know how to limit the user's input to two digits only. For example the person can input "1ABC" and the program will give the binary representation and I need it to only accept two digit only like for example "1A".
#include<stdio.h>
#define MAX 1000
int main(){
char binaryNumber[MAX],hexaDecimal[MAX];
long int i=0;
printf("Enter a two digit hexadecimal number: ");
[Code] ....
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Jul 21, 2014
I have matrix in C with size m x n. Size n isn't known. I want to have operations on matrix such as : delete first element and find i-th element. (where size m woudn't be too big , from 10 to 50 columns).
What is more efficient to use, linked list or hash table? How can I map each column of matrix to different element of linked list or hash table; depends what I choose to use?
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Oct 13, 2014
Write a program that reads in the numeric representation of a date and prints it out in a formatted manner as the box below.
1. If the user entered an invalid number for the month it should display "Invalid Month"
2. If the user entered an invalid number for the date it should display "Invalid Date"
3. Check to see if the day is outside the range for that particular month
An example of the input and the output:
Enter the date: 1 24 2013
The date you entered is: 1242013
Im not sure on how to go about this problem, but this is what I have.
#include <stdio.h>
int main(void) {
int a, b, c;
int status;
printf("Enter the Date");
status = scanf("%d,%d,%d",&a, &b, &c);
printf(" The Date is : %d",status);
return 0;
}
Am I going about this right? Is there an easier or better way to go about it? All that happens is that the program reads the first number and spits that back out.
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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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Jun 15, 2014
changing a 9 digit integer into a new 9 digit integer through simple mathematical operations. For example, I need to change 123456789 into the new digit 456123789. Sometimes I need to change a 9 digit integer into an 8 digit integer. An example is 789062456 into 62789456. I can ONLY use simple mathematical operations (addition, subtraction, multiplication, division and modulo).
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Oct 15, 2014
Complete the function myitohex so that its converts 8-byte integer to string based hexadecimals.
Ex: printf("0x%s",myitohex(64,hex)); should printout "0x40" on the screen
char *myitohex(uint8_t i, char *result){
???
return result;
}
I wrote:
#include <stdio.h>
#include <stdint.h>
char *myitohex(uint8_t i, char *result){
*result = i + '0';
[Code] ....
0xp gets printed out which is wrong. I think *result = i + '0'; is wrong. What changes should i do on this row ?
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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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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 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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