C++ :: Saving Specific Bits From 64-bit Number

Jun 24, 2013

I have a 64-bit uint64_t number:

Code:
Primitive<uint64_t> b = 0xCCCCCCCC00000000; I need to save the first 31 (most important) bits - 7FFFFFFE.

I found this solution in the Internet:

Code:
start = (((b)>>(first)) & ((1<<(((last+1)-(first))))-1)); but in my case for this code:
Code: Primitive<uint64_t> start = (((b)>>(32)) & ((1<<(((63+1)-(32))))-1));

I get an error: left shift count >= width of type

And even if I change 63 to 62:

Code:
Primitive<uint64_t> start = (((b)>>(32)) & ((1<<(((62+1)-(32))))-1));

I get: error: integer overflow in expression

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C++ :: Retrieve Double Number - Store 8 Bits Of Number In One Field And 16 Bits In Another

May 14, 2013

I am working on a project where I need to retrive a double number and store 8 bits of the number in one field and the other 16 bits in another field. the code below gives me an error.

lata= lat>>8;
latb = (lat & 0xff);

The error states that & and >> are illegal for double. With this in mind, can I use these on a double. If not what can I do to achieve what I am trying to do?

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C++ :: Retrieving First Three Bits Of A Number

Apr 25, 2013

I am trying to retrieve the first three bits of a number. The code that I am using should work but it isn't giving me the correct result when trying certain numbers. Below is the code I am using:

unsigned short num1, num2 = 0;
unsigned short num = 65535// binary 111111111111111
num1 = num && 0x07;// gives me 1 but should give 7(111)
num2 = num >>3;//gives me 8191, which is correct

Why I am not getting the first three correct bits(111)?

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C++ :: How To Reverse Bits For A Number

Sep 3, 2013

I am working on a project where I need to reverse bits for a number.

For example, if I have 110111100000000 I need to reverse it to 0000000001111011.

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C :: Return Number Of Bits Set To True

Jan 3, 2015

The task is to return the number of bits set to true.Here is my code:

Code:

int cardinalityBS(PBitSet _this) {
int s, counter = 0;
for(s = 0; s < 31; s++) {
counter += _this->bits & 1;
_this->bits <<= 1;
}
return counter;
}

[code]....

The code is not working, since whenever I set _this->bits to a number, it returns me the wrong result.

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C++ :: Assign Number Of Bits By Variable In Bitset?

Nov 29, 2013

i want to assign number of bits by a variable in bitset? how to do that? like bitset<4> foo; instead of 4 i want to use some variable and later on by user i want to assign it! boost library or any other library!

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C :: How To Show All The Bits Of A Number Using Bitwise Shift Operator

Mar 30, 2013

how to show all the bits of a number using bitwise shift operator....and hence represent the number in 2's complement representation

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C# :: Saving And Using Random Number?

Sep 27, 2014

I have this random number

List<string> ImageList = new List<string>();
ImageList.Add("Assets/Images/Image_0.jpg");
ImageList.Add("Assets/Images/Image_1.jpg");
ImageList.Add("Assets/Images/Image_2.jpg");

[Code] .....

The problem is that It generates a random number that can be the same as the last time. So I figured out, that I need to save my random number so I can use it later, as a if statement.

If saved number == r then it generates a new number.

how to save my generated number on OnNavigatedFrom method.

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C :: Get Binary Number And Change Its Bits - Calling A Function Not Working

Apr 8, 2013

This code gets a binary number and change its bits. I have a problem with the "bits_up" function . Why this function not working?

Code:
#include <stdio.h>
#include <stdlib.h>
int bits_up(uint first,uint last,int *ptr);
int main(void)
{
uint first,last,bitUD;
int InputBinNumber[4],updatedNum[4];

[Code] ....

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C :: Calculate Number Of Bits In Type - Incorrect Result In Program

Feb 15, 2014

I have this simple program below:

Code:
#include <stdio.h>
#include <limits.h>
unsigned int rightrot(unsigned int x, unsigned int n) {

/* calculate number of bits in type */

size_t s = sizeof(x) * CHAR_BIT;

[Code] ....

The result it prints is 2684356604 on my 32-bit computer. The result I expect is as follows:
0xFF94 is 0000000000000000 1111111110010100 in binary.

Shift it right by 5:
0000000000000000 0000011111111100

Then take that result in shift it right by 27 (s is 32 and p is 5, so the difference is 27):
1111111110000000 0000000000000000

Now we use bitwise or:
0000000000000000 0000011111111100 | 1111111110000000 0000000000000000 = 1111111110000000 0000011111111100

That in decimal is 4286580732. So how does it come up with 2684356604?

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C :: Calculator - Input Specific Number?

Feb 11, 2013

In my calculator, I am trying to make it so that you put enter 1 to add, 2 to subtract, 3 to multiply, and 4 to divide. I am facing the issue of making it so that you must enter a number, however instead of it being any number, it must be 1, 2, 3, or 4, and if it is not any of those numbers, you must re-enter the number. Here is a little snippet of my code:

Code:

printf("Please enter 1 to add, 2 to subtract, 3 to multiply, or 4 to multiply: ");
while (scanf("%d", &input) != 1) {
while (getchar() != '
');
printf("Invalid option. Please try again: ");

[Code] ....

how I can make the loop affect specific numbers.

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C++ :: Create A Specific Number Of For Loops Each In Another Loop

Sep 18, 2014

I want to create a specific number of for loops each in another loop, as in example:

for(i=0;i<9;i++)
{
for(j=0;j<9;j++)
{
for(k=0;k<9;k++)
{
//some stuff
}
}
}

In this example there are 3 loops, but what if i want to create e.g. 10 such loops, and program reads a number of loops from a txt? It is needed for checking numbers.

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C/C++ :: Counting Specific Amount Of Times A Number Shows Up

Apr 11, 2015

Ok, so I am writing this program with 10 different functions, and one of those functions needs to count how many times 0 appears in a text file. I've done this before, but I am so stumped right now. Should I get the numbers from the 2d array I have, or should I just use the text file here? Here is what I have right now:

int toursMissed(int scores[][COLS]){
int counter;
for(counter=0;counter<=96;counter++){
if(scores==0){
counter++;
return counter;
}
}

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C Sharp :: Assign A Specific Number To Each Letter In A Sentence?

Feb 14, 2014

I have a string - a whole sentence that I want to assign a number to each letter, space, comma and period etc. So all "A's" will have the same number, all "B's" will have another number etc. I don't want to use the ASCII numbers because they all need to be sequential and some of the punctuation isn't. I have put the string into a char array to separate each character out and was thinking about running it through a loop with if statements for each letter and assigning numbers there and then saving the numbers in the order they appear into a list as a string but I keep coming up with errors so I don't know how to do it or if there is a better way to accomplish what I'm trying to do.

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C/C++ :: How To Ask A User To Enter Date And ISBN Number In Specific Format

Dec 4, 2014

I don't know how to ask the user to enter the date in this format (DD/MM/YY) and ISBN number with hyphens.

After user enter date and ISBN number, it should look like this:

Date: 5/24/12
ISBN: 0-000-12345-0
#include <iostream>
#include <string>
using namespace std;
int main() {
string date;//MM/DD/YY Format

[Code] ....

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C++ :: Determine Number Of Times Change Each Specific Character In String To Make It Palindrome

Feb 19, 2015

I'm trying to determine the number of times I have to change each specific character in a string to make it a palindrome. You can only change a character one at a time from the end.

Example: "abc" -> "abb" -> "aba" should print 2. "aba" will print 0 because it's already a palindrome. "abcd" -> "abcc" -> "abcb" -> "abca" -> "abba" will print 4 because it took 4 changes to make a palindrome.

I'm not too sure how to approach this - I figured out the case where if it's a palindrome (if reversed string is the same) then it'll print out a 0.

int main() {
int number;
cin >> number; //expecting a number for first line user input
for (int i = 0; i < number; i++) {
string str;

[Code] ....

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C++ :: How To Make Specific Character Show Up Specific Amount Of Times

Mar 5, 2013

How do I make a specific character show up a specific amount of times?

Like I am generating a random number then I need to make "|" show up that many times on the screen.

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C++ :: Assigning Bits A Value Of 0

Feb 12, 2014

I am having a problem assigning bits a value of 0. The data is a 16 bit integer the bits greater than the 12th bit have garbage either a 0 or a 1. I would like to assign all bits greater than 12th bit the value 0 no matter what their values are. Whats the best approach.

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C++ :: Getting Bits In RDX After Multiply (x64)

Aug 13, 2013

Using the old fashioned (unsigned) multiplication instruction in x64 assembly multiplies RAX (64 bit register) by a 64 bit register. The answer is stored in RDX:RAX (i.e. the answer is 128 bits). Is there any way, using native c++ to get the value in RDX (higher 64 bits)? One I can think of is: right/(limit/left) e.g. if we are limited to a byte then 97*123 would overflow:

97/(255/123) = 46 times, which is RDX's (if it was one byte) value. But this is too inefficient. Is there a fast way?

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C++ :: Shifting Bits Away And Back

Mar 25, 2014

Value x is a 32-bit unsigned integer 3:

00000000000000000000000000000011

If we use bitwise-shift to shift all bits to the right by 2, x is 0:

00000000000000000000000000000000

If we then do a bitwise leftshift on x by 30, do we end up with:

11000000000000000000000000000000
or
00000000000000000000000000000000

In other words, when we perform right shift which clips away the least most significant bits, and then do a left shift, is it possible for those bits to reappear?

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C++ :: How To Set Certain Bits Of Unsigned Short

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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C++ :: How To Write Bits To A Disk

Mar 30, 2014

I'm trying to write a program that writes data to a disk in C++ without caring about it's file system. Here is what I can do so far:

#include <iostream>
#include <unistd.h>
#include <fcntl.h>
using namespace std;
char buffer[] = "Wow! I'm writing this data to a disk without puttting it into a file!";
int main(){
int Disk=open("/dev/sdb",O_RDWR);
write(Disk,buffer,sizeof(buffer));
close(Disk);
return 0;}

But this program can only write ASCII characters to the disk. But what if I want to mainipulate bits on the disk, how would I do that?

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C/C++ :: How To Locate The Lowest 8 Bits In A 64 Bit Key

Jul 15, 2014

I am trying to encrypt a plaintext using DES in C. I read about the algorithm and how it works, but when i came to write the code i struggled. :

How to locate the lowest 8-bits in a 64-bit key ?

How to shuffle the plaintext according to the algorithm description ? (I read about bitwise operations, but i still cannot understand how i can use them to transfer for example the 5th bit to the location of the 30th bit)

Left shifting the key would not wrap the bits, so i just bitwise or with a mask that will add the bits that did not wrap around?

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C/C++ :: Add 8 Bits - Return The Character

Oct 10, 2014

I'm working on an assignment where I have to read an image in the PPM format. This format consists of a header that contains the parameters and the rest is raw bits.

I have to work with a modified PPM image that contains a secret message. This message is stored in the first X number of bytes. To decode a single character I would have to look at the lowest level bit of 8 bytes and return that as a character, then repeat this for the length of the message.

The code below is what I have so far, but I do not get the expected output but instead I get smiley-faces.... or other ASCII characters depending on the shift.

char buffer = 0;
int MsgSize =(size*8);
int nRead = 0;
printf("The secret message is displayed below: ");
for(i; i<MsgSize; i++) {

[Code] ....

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C# :: Sbyte To Int - Copy Only Bits

Jan 15, 2014

I just have a short question! I have an sbyte and I want to convert it to an int, but I do not want a value conversion, just to copy the bits, such that the negative numbers in the sbyte will be their complement in the int (-12 in sbyte -> 244 in int)... How can I do that?las

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C :: Decimal To Binary Converter (8-bits)

Sep 9, 2014

I was trying to program an decimal to binary converter (8-bits) in C. I am a complete beginner so I tried to put the 1's and 0's of the binary number as they come without reversing the order for beginning. I have seen example on the internet but didn't understand them so I decided to write it as I understood it. So, I typed the code as shown below:

Code:
#include <stdio.h>
#include <stdlib.h>
int main() {
int number;
int BitNum[8], x;

[Code] ....

The problem with the code is that if binary form has 0s in it then program displays a random number instead of a 0. For example if decimal is 7, it should print out 11100000 but it displays only 111(and some stupid numbers instead of 0). I have tried to solve it but failed.

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