I need to get bits of a character. I haven't used C++ bitwise operators before, and I can't figure out what I'm doing wrong.
int main()
{
bool bits[8];
char c = static_cast<char>(0b11101101);
for(int i = 0; i < 8; i++) {
bits[i] = (c >> i) & 1;
}
for(int i = 0; i < 8; i++) {
std::cout << bits[i];
}
}
//output: 10110111
Just change your first loop to:
for(int i = 0; i < 8; i++) {
bits[7-i] = (c >> i ) & 1;
}
Related
image of shape
I have no issues with first 4 rows. 5th row is the problem. I am required to use loops but dont know how i am suppose to print 6 (-.*) with 0 spaces when all rows above follow a pattern.
Something like this should work for you
for (int i = 1; i <= 6; i++) {
for (int j = 28 - i * 3; j >= 0; j--) {
std::cout << " ";
}
for (int j = 0; j < i; j++) {
std::cout << "-.*";
}
std::cout << std::endl;
if (i == 4) i++;
}
Basically check when you are on the 4th row and just have it skip a row by incrementing your row index loop.
Something like this?
std::string repeat(std::string s, int n) {
std::string repeat;
for (int i = 0; i < n; ++i)
repeat += s;
return repeat;
}
int main()
{
int PADDING = 20;
int MAX = 7;
for (int i = 1; i < MAX; ++i) {
if (i == 5) continue;
std::string padding(3*(PADDING-MAX-i), ' ');
std::cout << padding << repeat("-.*", i) << std::endl;
}
}
Output:
-.*
-.*-.*
-.*-.*-.*
-.*-.*-.*-.*
-.*-.*-.*-.*-.*-.*
Live demo:
http://cpp.sh/6mtpx
In C (not C++):
#include <stdio.h>
int main(void) {
int height = 5;
char txt[3*height+1];
char sym[]= "-.*";
for(int i=0; i<3*height; ++i) txt[i]=sym[i%3];
txt[3*height]=0;
for(int i=0; i<height; ++i)
printf("%s%*.*s\n", (i+1==height)? &txt[3*(height-1)] : "", 3*(height+(i+1<height)), (i+1)*3, txt);
return 0;
}
Output:
Success #stdin #stdout 0s 5476KB
-.*
-.*-.*
-.*-.*-.*
-.*-.*-.*-.*
-.*-.*-.*-.*-.*-.*
IDEOne Link
I try to design a program that implements the multiplication between two big integers(Using C++). But after I complete it, I found that if I input the two integers by the command arguments, the results would be sometimes very weird and sometimes right. Please help me figure out the reason and tell me how to fix it. Thanks (The main function that implements the function of multiplication between two big integers is mul() ).
#include <iostream>
#include <cstring>
#include <stdlib.h>
using namespace std;
void mul(char *c1, char *c2, int len1, int len2);
void printArr(char *c1, char *c2, int len1, int len2);
int main(int argc, char **argv)
{
if (argv[1] != NULL)
{
char cArr1[500], cArr2[500];
for (int i = 0; i < strlen(argv[1]); i++)
{
cArr1[i] = argv[1][i];
}
for (int i = 0; i < strlen(argv[2]); i++)
{
cArr2[i] = argv[2][i];
}
int len1 = strlen(cArr1);
int len2 = strlen(cArr2);
printArr(cArr1, cArr2, len1, len2);
(len1 > len2) ? mul(cArr1, cArr2, len1, len2) : mul(cArr2, cArr1, len2, len1);
exit(100);
}
while (true)
{
cout << "Please input two integers" << endl;
char cArr1[500], cArr2[500];
cin >> cArr1;
if (cArr1[0] == 'q' && cArr1[1] == 'u' && cArr1[2] == 'i' && cArr1[3] == 't')
{
exit(1000);
}
cin >> cArr2;
int parity = 0;
int len1 = strlen(cArr1);
int len2 = strlen(cArr2);
printArr(cArr1, cArr2, len1, len2);
if (cArr1[0] == '-')
{
for (int i = 1; i < len1; i++)
{
cArr1[i - 1] = cArr1[i];
}
parity++;
len1--;
}
if (cArr2[0] == '-')
{
for (int i = 1; i < len2; i++)
{
cArr2[i - 1] = cArr2[i];
}
parity++;
len2--;
}
bool isDigit = true;
for (int i = 0; i < len1; i++)
{
if (!isdigit(cArr1[i]))
{
isDigit = false;
}
}
for (int i = 0; i < len2; i++)
{
if (!isdigit(cArr2[i]))
{
isDigit = false;
}
}
if (!isDigit)
{
cout << "\rInvalid input. Try again" << endl;
continue;
}
if (parity % 2 != 0)
{
cout << "-";
}
(len1 > len2) ? mul(cArr1, cArr2, len1, len2) : mul(cArr2, cArr1, len2, len1);
}
}
void mul(char *bigger, char *smaller, int bigLen, int smallLen)
{
int *bigNum = new int[bigLen];
int *smallNum = new int[smallLen];
for (int i = 0; i < bigLen; i++)
{
bigNum[i] = bigger[bigLen - i - 1] - '0';
}
for (int i = 0; i < smallLen; i++)
{
smallNum[i] = smaller[smallLen - i - 1] - '0';
}
int res[30];
for (int i = 0; i < 30; i++)
{
res[i] = 0;
}
for (int i = 0; i < smallLen; i++)
{
for (int j = 0; j < bigLen; j++)
{
res[i + j] += bigNum[j] * smallNum[i];
}
}
for (int i = 0; i < bigLen + smallLen; i++)
{
int digit = res[i] % 10;
int carry = res[i] / 10;
res[i] = digit;
res[i + 1] += carry;
}
bool null = false;
for (int i = bigLen + smallLen - 1; i >= 0; i--)
{
if (res[i] != 0 && res[i + 1] == 0)
{
null = true;
}
if (null)
{
cout << res[i];
}
}
cout << endl;
}
void printArr(char *c1, char *c2, int len1, int len2)
{
for (int i = 0; i < len1; i++)
{
cout << c1[i];
}
cout << " * ";
for (int i = 0; i < len2; i++)
{
cout << c2[i];
}
cout << " = ";
}
Just initialize your char arrays to empty ones:
char cArr1[500] = {};
char cArr2[500] = {};
then, for the sake of clarity, assign the lengths from your arguments to two integers, casting them since the compiler might warn you about incompatibility between size_t and int.
int lenArg1 = 0;
int lenArg2 = 0;
lenArg1 = (int)strlen ( argv[1] );
lenArg2 = (int)strlen ( argv[2] );
Then, printing the lengths len1 and len2 for debugging purposes only:
int len1 = strlen ( cArr1 );
int len2 = strlen ( cArr2 );
cout << "len1 >> " + to_string(len1) <<endl;
cout << "len2 >> " + to_string(len2) <<endl;
In fact, as #Kevin SUN mentioned, it was possible that your argument reading steps were missing the null characters, however, after running some tests it seems to work fine just by initializing the char arrays.
Also, as mentioned in the comments you need to increase the size reserved for res array, I did it to 500
Compiled with g++ -Wall main.cpp -o calc.exe and running: calc 10 100
Without initialization you get problems like:
after initializing, the output works just fine:
Alright so I have created this code. However, when i run it, it stops when it displays 104 for the counter??? I am so frustrated because I don't know how this could happen. The purpose of the code is to do the typical magic number output where the rows all add up to the same thing, the columns all add up to the same thing, and the diaganols all add up to the same thing. I believe the functions to do these calculations are correct, but the counter keeps stopping short of the 10000 attempts I am trying to do.
#include <iostream>
#include<time.h>
#include<stdlib.h>
using namespace std;
void getrandom();
void insertnumber(int n);
bool magic();
void create();
const int rows = 3;
const int cols = 3;
int arr[rows][cols] = { {0,0,0}, {0,0,0} , {0,0,0} };
int main() {
int counter = 0;
do
{
counter++;
cout << counter << endl;
getrandom();
if (counter == 100000)
break;
} while (!magic());
create();
cout << "It took " << counter << " tries." << endl;
return 0;
}
void getrandom() {
int n = 0;
const int size = 9;
int oldnum[size];
for (int i = 0; i < rows * cols; i++) {
oldnum[i] = 0;
}
srand(time(NULL)); // had to import the new libraries to use this
bool used = true;
for (int i = 0; i < size; i++) {
do
{
used = true;
n = rand() % 9 + 1;
if (oldnum[n - 1] == 0)
{
oldnum[n - 1] = n;
used = false;
}
} while (used);
insertnumber(n);
}
}
void insertnumber(int n) {
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
if (arr[i][j] == 0) {
arr[i][j] = n;
return;
}
}
}
}
bool magic() {
int rowsum = arr[0][0] + arr[0][1] + arr[0][2];
for (int i = 1; i < cols; i++)
{
if (arr[i][0] + arr[i][1] + arr[i][2] != rowsum)
return false;
}
for (int j = 0; j < rows; j++)
{
if (arr[0][j] + arr[1][j] + arr[2][j] != rowsum)
return false;
}
if (arr[0][0] + arr[1][1] + arr[2][2] != rowsum)
return false;
if (arr[0][2] + arr[1][1] + arr[2][0] != rowsum)
return false;
return true;
}
void create() {
{
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
cout << arr[i][j] << " ";
}
cout << endl;
}
}
}
You can try using a debugger for such problems.
I think you code crashes because of this:
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
It looks like you mean j < cols here :)
Check line 76. When I compile and run the code, line 76 is where the exception is thrown.
This line specifically
arr[i][j] = n;
It seems your insertnumber() function is the culprit.
I have the follow code below to generate a scrambled state array, however, it does not seem to be generating the properly randomized state array for the key (51323).
unsigned char* generateStateArray(unsigned long key) {
unsigned char s[256];
//Load the state array from 1-255
for (int i = 0; i < 256; i++) {
s[i] = i;
}
//Get the binary representation of the key
unsigned long n = key;
int binary[64];
for (int i = 0; i < 64; i++) {
binary[i] = 0;
std::cout << binary[i];
}
std::cout << std::endl;
for (int i = 0; n > 0; i++) {
binary[i] = n % 2;
n /= 2;
}
//Randomize the entries
int j = 0;
for (int i = 0; i < 256; i++) {
j = (j + binary[i % 64] + s[i]) & 255;
char c = s[i];
s[i] = s[j];
s[j] = c;
}
}
The output for S should look like:
But it gives me this output:
Any idea what I'm doing wrong and how I can fix it?
I am currently working on a program that prints a 5 variable truth table. I am using a 2d array. My code currently produces the table, but says it is corrupt and "the stack around the variable "table" was corrupted. Any help?
#include <iostream>
using namespace std;
int main() {
bool table[5][32];
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
table[i][j] = ((i >> j)& 1);
}
}
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
cout << table[i][j] << " ";
}
cout << endl;
}
return 0;
}
This is homework, so I would like to understand it, not just have an answer.
The index is wrong. Only table[0] to table[4] are available, so accessing table[5] to table[31] is illegal.
Try this:
#include <iostream>
using namespace std;
int main() {
bool table[32][5]; // swap 32 and 5
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
table[i][j] = ((i >> j)& 1);
}
}
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
cout << table[i][j] << " ";
}
cout << endl;
}
return 0;
}
There is attempt to read out of bound values from array.
If you need 5x32 matrix Use code below:
for (int i = 0; i < 5; i++) { // 32-> 5
for (int j = 0; j < 32; j++) { // 5->32
If you need 32x5 matrix then replace code below:
bool table[32][5]; //it was table[5][32];