2 replies to this topic

[hetra]

Hello all,

Excuse me if this has already been asked alot-but I did Google it and have done research-but alot of the snippets I've found don't work properly.

I want to convert a decimal integer to a binary number. I used atoi() to convert the user's input to an integer but now I want to convert that integer to binary.

Advice, code, etc. would be great.

[Skippy]

#include <iostream>

#include <string>


#define BITS_IN_INT (8*4)


//post-condition : delete is used on returned pointer

std::string* CreateBinaryString( int number );


int main()

{

    using namespace std;


    string* str = 0;

    

    for( int i = 0; i < 10; i++ )

    {   


        str = CreateBinaryString( i );

        cout << i << "\t" << *str << "\n";

        delete str;

    }   

    

    return 0;

}


std::string* CreateBinaryString( int number )

{

    char str[BITS_IN_INT+1];



    for( int i = 0; i < BITS_IN_INT; i++ )

    {   

        str[BITS_IN_INT-i-1] = ((number) & (0x0001<<i))? '1':'0';    


    }   


    str[BITS_IN_INT] = '\0';


    std::string* ret = new std::string(str);


    return ret;

}

josh@josh-desktop:~/Desktop$ g++ PrintBinary.cpp

josh@josh-desktop:~/Desktop$ a.out

0	00000000000000000000000000000000

1	00000000000000000000000000000001

2	00000000000000000000000000000010

3	00000000000000000000000000000011

4	00000000000000000000000000000100

5	00000000000000000000000000000101

6	00000000000000000000000000000110

7	00000000000000000000000000000111

8	00000000000000000000000000001000

9	00000000000000000000000000001001

[Alexander]

Or if you prefer to use C:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BITS_IN_INT (sizeof(int) * 8)

char* CreateBinaryString(int number);

int main(void) {
  int i;
  char* str;
  for(i = 0;i < 10; i++) {
    str = CreateBinaryString(i);
    printf("%i\t%s\n", i, str);
    free(str);
  }
  return 0;
}

char* CreateBinaryString(int number) {
  char str[BITS_IN_INT+1];
  int i;
  for(i = 0; i < BITS_IN_INT; i++) {   
    str[BITS_IN_INT-i-1] = ((number) & (1 << i)) ? '1':'0';    
  }   
  str[BITS_IN_INT] = '\0';
  
  char* ret = (char*) malloc(BITS_IN_INT + 1);
  strncpy(ret, str, BITS_IN_INT + 1);
  return ret;
}