decimal to binary

[muhsid]

This code gives result as binary of the array values written eg: {15,127,7} the output was 11111111111111, can anyone help to modify this to get an output with fixed binary number irrespective of the number given. that means whatever value smaller value i am typing for 127 i should get output with 7 bit .
#include <iostream>
#include<vector>
using namespace std;
int main()
{
long binary_number ;
vector <int> binary;
int decimals[3]={15,127,7};

while ( decimals[2] >= 1 )
{
binary_number =decimals[2] % 2;
decimals[2] /= 2;
binary.push_back(binary_number);

}

for ( int i = (int) binary.size()-1; i >= 0; i-- )
//cout << binary[i] << "";


while ( decimals[1] >= 1 )
{
binary_number =decimals[1] % 2;
decimals[1] /= 2;
binary.push_back(binary_number);

}

for ( int i = (int) binary.size()-1; i >= 0; i-- )

while ( decimals[0] >= 1 )
{
binary_number =decimals[0] % 2;
decimals[0] /= 2;
binary.push_back(binary_number);

}

for ( int i = (int) binary.size()-1; i >= 0; i-- )
cout << binary[i] << "";
return 0;

}

[LB]

You could set the formatted output to pad with '0' with a width of 8.

[giblit]

You could use LB's method with std::setfill¹ and std::setw² from the iomanip³ library

Or even use a std::bitset⁴ with the number of bits you want it to be. Then when you output use tostring⁵ method if you want it in binary otherwise use the toulong⁶ or toullong⁷ (long long) methods for decimal.

¹ http://www.cplusplus.com/reference/iomanip/setfill/?kw=setfill
² http://www.cplusplus.com/reference/iomanip/setw/
³ http://www.cplusplus.com/reference/iomanip/
⁴ http://www.cplusplus.com/reference/bitset/bitset/?kw=bitset
⁵ http://www.cplusplus.com/reference/bitset/bitset/to_string/
⁶ http://www.cplusplus.com/reference/bitset/bitset/to_ulong/
⁷ http://www.cplusplus.com/reference/bitset/bitset/to_ullong/

[edit]You could also use the fill constructor of std::vector and assign the fill to 0 and the size to be the number of bits you want it to be.
http://www.cplusplus.com/reference/vector/vector/vector/

cplusplus dot com wrote:

fill (2)
explicit vector (size_type n);
vector (size_type n, const value_type& val,
const allocator_type& alloc = allocator_type());

so say you want it to be an 8 bit (1 byte) it would look like std::vector<int> vec( 8 , 0 );[/edit]

[muhsid]

thank you LB & giblit