There isn't a binary conversion specifier in glibc normally.
It is possible to add custom conversion types to the printf() family of functions in glibc. See register_printf_function for details. You could add a custom %b conversion for your own use, if it simplifies the application code to have it available.
Here is an example of how to implement a custom printf formats in glibc.
You could use a small table to improve speed1. Similar techniques are useful in the embedded world, for example, to invert a byte:
const char *bit_rep[16] = {
[ 0] = "0000", [ 1] = "0001", [ 2] = "0010", [ 3] = "0011",
[ 4] = "0100", [ 5] = "0101", [ 6] = "0110", [ 7] = "0111",
[ 8] = "1000", [ 9] = "1001", [10] = "1010", [11] = "1011",
[12] = "1100", [13] = "1101", [14] = "1110", [15] = "1111",
};
void print_byte(uint8_t byte)
{
printf("%s%s", bit_rep[byte >> 4], bit_rep[byte & 0x0F]);
}
1 I'm mostly referring to embedded applications where optimizers are not so aggressive and the speed difference is visible.
const char* byte_to_binary(int x)
{
static char b[sizeof(int)*8+1] = {0};
int y;
long long z;
for (z = 1LL<<sizeof(int)*8-1, y = 0; z > 0; z >>= 1, y++) {
b[y] = (((x & z) == z) ? '1' : '0');
}
b[y] = 0;
return b;
}
I optimized the top solution for size and C++-ness, and got to this solution:
inline std::string format_binary(unsigned int x)
{
static char b[33];
b[32] = '\0';
for (int z = 0; z < 32; z++) {
b[31-z] = ((x>>z) & 0x1) ? '1' : '0';
}
return b;
}
The following function returns binary representation of given unsigned integer using pointer arithmetic without leading zeros:
const char* toBinaryString(unsigned long num)
{
static char buffer[CHAR_BIT*sizeof(num)+1];
char* pBuffer = &buffer[sizeof(buffer)-1];
do *--pBuffer = '0' + (num & 1);
while (num >>= 1);
return pBuffer;
}
Note that there is no need to explicity set NUL terminator, because buffer repesents an object with static storage duration, that is already filled with all-zeros.
This can be easily adapted to unsigned long long (or another unsigned integer) by simply modifing type of num formal parameter.
The CHAR_BIT requires <limits.h> to be included.
Here is an example usage:
int main(void)
{
printf(">>>%20s<<<\n", toBinaryString(1));
printf(">>>%-20s<<<\n", toBinaryString(254));
return 0;
}
with its desired output as:
>>> 1<<<
>>>11111110 <<<
The combination of functions + macro at the end of this answer can help you.
Use it like that:
float float_var = 9.4;
SHOW_BITS(float_var);
Which will output: Variable 'float_var': 01000001 00010110 01100110 01100110
Note that it is very general and can work with pretty much any type. For instance:
struct {int a; float b; double c;} struct_var = {1,1.1,1.2};
SHOW_BITS(struct_var);
Which will output:
Variable `struct_var`: 00111111 11110011 00110011 00110011 00110011 00110011 00110011 00110011 00111111 10001100 11001100 11001101 00000000 00000000 00000000 00000001
Here's the code:
#define SHOW_BITS(a) ({ \
printf("Variable `%s`: ", #a);\
show_bits(&a, sizeof(a));\
})
void show_uchar(unsigned char a)
{
for(int i = 7; i >= 0; i-= 1)
printf("%d", ((a >> i) & 1));
}
void show_bits(void* a, size_t s)
{
unsigned char* p = (unsigned char*) a;
for(int i = s-1; i >= 0 ; i -= 1) {
show_uchar(p[i]);
printf(" ");
}
printf("\n");
}
Based on @William Whyte's answer, this is a macro that provides int8,16,32 & 64 versions, reusing the INT8 macro to avoid repetition.
/* --- PRINTF_BYTE_TO_BINARY macro's --- */
#define PRINTF_BINARY_PATTERN_INT8 "%c%c%c%c%c%c%c%c"
#define PRINTF_BYTE_TO_BINARY_INT8(i) \
(((i) & 0x80ll) ? '1' : '0'), \
(((i) & 0x40ll) ? '1' : '0'), \
(((i) & 0x20ll) ? '1' : '0'), \
(((i) & 0x10ll) ? '1' : '0'), \
(((i) & 0x08ll) ? '1' : '0'), \
(((i) & 0x04ll) ? '1' : '0'), \
(((i) & 0x02ll) ? '1' : '0'), \
(((i) & 0x01ll) ? '1' : '0')
#define PRINTF_BINARY_PATTERN_INT16 \
PRINTF_BINARY_PATTERN_INT8 PRINTF_BINARY_PATTERN_INT8
#define PRINTF_BYTE_TO_BINARY_INT16(i) \
PRINTF_BYTE_TO_BINARY_INT8((i) >> 8), PRINTF_BYTE_TO_BINARY_INT8(i)
#define PRINTF_BINARY_PATTERN_INT32 \
PRINTF_BINARY_PATTERN_INT16 PRINTF_BINARY_PATTERN_INT16
#define PRINTF_BYTE_TO_BINARY_INT32(i) \
PRINTF_BYTE_TO_BINARY_INT16((i) >> 16), PRINTF_BYTE_TO_BINARY_INT16(i)
#define PRINTF_BINARY_PATTERN_INT64 \
PRINTF_BINARY_PATTERN_INT32 PRINTF_BINARY_PATTERN_INT32
#define PRINTF_BYTE_TO_BINARY_INT64(i) \
PRINTF_BYTE_TO_BINARY_INT32((i) >> 32), PRINTF_BYTE_TO_BINARY_INT32(i)
/* --- end macros --- */
#include <stdio.h>
int main() {
long long int flag = 1648646756487983144ll;
printf("My Flag "
PRINTF_BINARY_PATTERN_INT64 "\n",
PRINTF_BYTE_TO_BINARY_INT64(flag));
return 0;
}
This outputs:
My Flag 0001011011100001001010110111110101111000100100001111000000101000
For readability you may want to add a separator for eg:
My Flag 00010110,11100001,00101011,01111101,01111000,10010000,11110000,00101000
None of the previously posted answers are exactly what I was looking for, so I wrote one. It is super simple to use %B with the printf!
/*
* File: main.c
* Author: Techplex.Engineer
*
* Created on February 14, 2012, 9:16 PM
*/
#include <stdio.h>
#include <stdlib.h>
#include <printf.h>
#include <math.h>
#include <string.h>
static int printf_arginfo_M(const struct printf_info *info, size_t n, int *argtypes)
{
/* "%M" always takes one argument, a pointer to uint8_t[6]. */
if (n > 0) {
argtypes[0] = PA_POINTER;
}
return 1;
}
static int printf_output_M(FILE *stream, const struct printf_info *info, const void *const *args)
{
int value = 0;
int len;
value = *(int **) (args[0]);
// Beginning of my code ------------------------------------------------------------
char buffer [50] = ""; // Is this bad?
char buffer2 [50] = ""; // Is this bad?
int bits = info->width;
if (bits <= 0)
bits = 8; // Default to 8 bits
int mask = pow(2, bits - 1);
while (mask > 0) {
sprintf(buffer, "%s", ((value & mask) > 0 ? "1" : "0"));
strcat(buffer2, buffer);
mask >>= 1;
}
strcat(buffer2, "\n");
// End of my code --------------------------------------------------------------
len = fprintf(stream, "%s", buffer2);
return len;
}
int main(int argc, char** argv)
{
register_printf_specifier('B', printf_output_M, printf_arginfo_M);
printf("%4B\n", 65);
return EXIT_SUCCESS;
}
No standard and portable way.
Some implementations provide itoa(), but it's not going to be in most, and it has a somewhat crummy interface. But the code is behind the link and should let you implement your own formatter pretty easily.
A small utility function in C to do this while solving a bit manipulation problem. This goes over the string checking each set bit using a mask (1<
void
printStringAsBinary(char * input)
{
char * temp = input;
int i = 7, j =0;;
int inputLen = strlen(input);
/* Go over the string, check first bit..bit by bit and print 1 or 0
**/
for (j = 0; j < inputLen; j++) {
printf("\n");
while (i>=0) {
if (*temp & (1 << i)) {
printf("1");
} else {
printf("0");
}
i--;
}
temp = temp+1;
i = 7;
printf("\n");
}
}
Here's is a very simple one:
int print_char_to_binary(char ch)
{
int i;
for (i=7; i>=0; i--)
printf("%hd ", ((ch & (1<<i))>>i));
printf("\n");
return 0;
}
Print Binary for Any Datatype
// Assumes little endian
void printBits(size_t const size, void const * const ptr)
{
unsigned char *b = (unsigned char*) ptr;
unsigned char byte;
int i, j;
for (i = size-1; i >= 0; i--) {
for (j = 7; j >= 0; j--) {
byte = (b[i] >> j) & 1;
printf("%u", byte);
}
}
puts("");
}
Test:
int main(int argv, char* argc[])
{
int i = 23;
uint ui = UINT_MAX;
float f = 23.45f;
printBits(sizeof(i), &i);
printBits(sizeof(ui), &ui);
printBits(sizeof(f), &f);
return 0;
}
Here is a quick hack to demonstrate the techniques for what you want.
#include <stdio.h> /* printf */
#include <string.h> /* strcat */
#include <stdlib.h> /* strtol */
const char *byte_to_binary(int x)
{
static char b[9];
b[0] = '\0';
int z;
for (z = 128; z > 0; z >>= 1) {
strcat(b, ((x & z) == z) ? "1" : "0");
}
return b;
}
int main(void) {
{
/* binary string to int */
char *tmp;
char *b = "0101";
printf("%d\n", strtol(b, &tmp, 2));
}
{
/* byte to binary string */
printf("%s\n", byte_to_binary(5));
}
return 0;
}
#include <stdio.h>
#include <conio.h>
void main()
{
clrscr();
printf("Welcome\n\n\n");
unsigned char x='A';
char ch_array[8];
for(int i=0; x!=0; i++)
{
ch_array[i] = x & 1;
x = x >>1;
}
for(--i; i>=0; i--)
printf("%d", ch_array[i]);
getch();
}
void print_bits (uintmax_t n)
{
for (size_t i = 8 * sizeof (int); i-- != 0;)
{
char c;
if ((n & (1UL << i)) != 0)
c = '1';
else
c = '0';
printf ("%c", c);
}
}
Not a cover-absolutely-everywhere solution but if you want something quick, and easy to understand, I'm suprised no one has proposed this solution yet.
void DisplayBinary(int n)
{
int arr[8];
int top =-1;
while (n)
{
if (n & 1)
arr[++top] = 1;
else
arr[++top] = 0;
n >>= 1;
}
for (int i = top ; i > -1;i--)
{
printf("%d",arr[i]);
}
printf("\n");
}
Based on @ideasman42's suggestion in his answer, this is a macro that provides int8,16,32 & 64 versions, reusing the INT8 macro to avoid repetition.
/* --- PRINTF_BYTE_TO_BINARY macro's --- */
#define PRINTF_BINARY_SEPARATOR
#define PRINTF_BINARY_PATTERN_INT8 "%c%c%c%c%c%c%c%c"
#define PRINTF_BYTE_TO_BINARY_INT8(i) \
(((i) & 0x80ll) ? '1' : '0'), \
(((i) & 0x40ll) ? '1' : '0'), \
(((i) & 0x20ll) ? '1' : '0'), \
(((i) & 0x10ll) ? '1' : '0'), \
(((i) & 0x08ll) ? '1' : '0'), \
(((i) & 0x04ll) ? '1' : '0'), \
(((i) & 0x02ll) ? '1' : '0'), \
(((i) & 0x01ll) ? '1' : '0')
#define PRINTF_BINARY_PATTERN_INT16 \
PRINTF_BINARY_PATTERN_INT8 PRINTF_BINARY_SEPARATOR PRINTF_BINARY_PATTERN_INT8
#define PRINTF_BYTE_TO_BINARY_INT16(i) \
PRINTF_BYTE_TO_BINARY_INT8((i) >> 8), PRINTF_BYTE_TO_BINARY_INT8(i)
#define PRINTF_BINARY_PATTERN_INT32 \
PRINTF_BINARY_PATTERN_INT16 PRINTF_BINARY_SEPARATOR PRINTF_BINARY_PATTERN_INT16
#define PRINTF_BYTE_TO_BINARY_INT32(i) \
PRINTF_BYTE_TO_BINARY_INT16((i) >> 16), PRINTF_BYTE_TO_BINARY_INT16(i)
#define PRINTF_BINARY_PATTERN_INT64 \
PRINTF_BINARY_PATTERN_INT32 PRINTF_BINARY_SEPARATOR PRINTF_BINARY_PATTERN_INT32
#define PRINTF_BYTE_TO_BINARY_INT64(i) \
PRINTF_BYTE_TO_BINARY_INT32((i) >> 32), PRINTF_BYTE_TO_BINARY_INT32(i)
/* --- end macros --- */
#include <stdio.h>
int main() {
long long int flag = 1648646756487983144ll;
printf("My Flag "
PRINTF_BINARY_PATTERN_INT64 "\n",
PRINTF_BYTE_TO_BINARY_INT64(flag));
return 0;
}
This outputs:
My Flag 0001011011100001001010110111110101111000100100001111000000101000
For readability you can change :#define PRINTF_BINARY_SEPARATOR to #define PRINTF_BINARY_SEPARATOR "," or #define PRINTF_BINARY_SEPARATOR " "
This will output:
My Flag 00010110,11100001,00101011,01111101,01111000,10010000,11110000,00101000
or
My Flag 00010110 11100001 00101011 01111101 01111000 10010000 11110000 00101000
There is also an idea to convert the number to hexadecimal format and then to decode each hexadecimal cipher to four "bits" (ones and zeros). sprintf can do bit operations for us:
const char* binary(int n) {
static const char binnums[16][5] = { "0000","0001","0010","0011",
"0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111" };
static const char* hexnums = "0123456789abcdef";
static char inbuffer[16], outbuffer[4*16];
const char *i;
sprintf(inbuffer,"%x",n); // hexadecimal n -> inbuffer
for(i=inbuffer; *i!=0; ++i) { // for each hexadecimal cipher
int d = strchr(hexnums,*i) - hexnums; // store its decimal value to d
char* o = outbuffer+(i-inbuffer)*4; // shift four characters in outbuffer
sprintf(o,"%s",binnums[d]); // place binary value of d there
}
return strchr(outbuffer,'1'); // omit leading zeros
}
puts(binary(42)); // outputs 101010
void binario(int num) {
for(int i=0;i<32;i++){
(num&(1<i))? printf("1"):
printf("0");
}
printf("\n");
}
Here's a version of the function that does not suffer from reentrancy issues or limits on the size/type of the argument:
#define FMT_BUF_SIZE (CHAR_BIT*sizeof(uintmax_t)+1)
char *binary_fmt(uintmax_t x, char buf[static FMT_BUF_SIZE])
{
char *s = buf + FMT_BUF_SIZE;
*--s = 0;
if (!x) *--s = '0';
for (; x; x /= 2) *--s = '0' + x%2;
return s;
}
Note that this code would work just as well for any base between 2 and 10 if you just replace the 2's by the desired base. Usage is:
char tmp[FMT_BUF_SIZE];
printf("%s\n", binary_fmt(x, tmp));
Where x is any integral expression.
void
print_binary(unsigned int n)
{
unsigned int mask = 0;
/* this grotesque hack creates a bit pattern 1000... */
/* regardless of the size of an unsigned int */
mask = ~mask ^ (~mask >> 1);
for(; mask != 0; mask >>= 1) {
putchar((n & mask) ? '1' : '0');
}
}
Here is a small variation of paniq's solution that uses templates to allow printing of 32 and 64 bit integers:
template<class T>
inline std::string format_binary(T x)
{
char b[sizeof(T)*8+1] = {0};
for (size_t z = 0; z < sizeof(T)*8; z++)
b[sizeof(T)*8-1-z] = ((x>>z) & 0x1) ? '1' : '0';
return std::string(b);
}
And can be used like:
unsigned int value32 = 0x1e127ad;
printf( " 0x%x: %s\n", value32, format_binary(value32).c_str() );
unsigned long long value64 = 0x2e0b04ce0;
printf( "0x%llx: %s\n", value64, format_binary(value64).c_str() );
Here is the result:
0x1e127ad: 00000001111000010010011110101101
0x2e0b04ce0: 0000000000000000000000000000001011100000101100000100110011100000
void PrintBinary( int Value, int Places, char* TargetString)
{
int Mask;
Mask = 1 << Places;
while( Places--) {
Mask >>= 1; /* Preshift, because we did one too many above */
*TargetString++ = (Value & Mask)?'1':'0';
}
*TargetString = 0; /* Null terminator for C string */
}
The calling function "owns" the string...:
char BinaryString[17];
...
PrintBinary( Value, 16, BinaryString);
printf( "yadda yadda %s yadda...\n", BinaryString);
Depending on your CPU, most of the operations in PrintBinary render to one or very few machine instructions.
Yet another approach to print in binary: Convert the integer first.
To print 6 in binary, change 6 to 110, then print "110".
Bypasses char buf[] issues.
printf() format specifiers, flags, & fields like "%08lu", "%*lX" still readily usable.
Not only binary (base 2), this method expandable to other bases up to 16.
Limited to smallish integer values.
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
unsigned long char_to_bin10(char ch) {
unsigned char uch = ch;
unsigned long sum = 0;
unsigned long power = 1;
while (uch) {
if (uch & 1) {
sum += power;
}
power *= 10;
uch /= 2;
}
return sum;
}
uint64_t uint16_to_bin16(uint16_t u) {
uint64_t sum = 0;
uint64_t power = 1;
while (u) {
if (u & 1) {
sum += power;
}
power *= 16;
u /= 2;
}
return sum;
}
void test(void) {
printf("%lu\n", char_to_bin10(0xF1));
// 11110001
printf("%" PRIX64 "\n", uint16_to_bin16(0xF731));
// 1111011100110001
}
One statement generic conversion of any integral type into the binary string representation using standard library:
#include <bitset>
MyIntegralType num = 10;
print("%s\n",
std::bitset<sizeof(num) * 8>(num).to_string().insert(0, "0b").c_str()
); // prints "0b1010\n"
Or just: std::cout << std::bitset<sizeof(num) * 8>(num);
/* Convert an int to it's binary representation */
char *int2bin(int num, int pad)
{
char *str = malloc(sizeof(char) * (pad+1));
if (str) {
str[pad]='\0';
while (--pad>=0) {
str[pad] = num & 1 ? '1' : '0';
num >>= 1;
}
} else {
return "";
}
return str;
}
/* example usage */
printf("The number 5 in binary is %s", int2bin(5, 4));
/* "The number 5 in binary is 0101" */
Do a function and call it
display_binary(int n)
{
long int arr[32];
int arr_counter=0;
while(n>=1)
{
arr[arr_counter++]=n%2;
n/=2;
}
for(int i=arr_counter-1;i>=0;i--)
{
printf("%d",arr[i]);
}
}
There is no formatting function in the C standard library to output binary like that. All the format operations the printf family supports are towards human readable text.
// m specifies how many of the low bits are shown.
// Replace m with sizeof(n) below for all bits and
// remove it from the parameter list if you like.
void print_binary(unsigned long n, unsigned long m) {
static char show[3] = "01";
unsigned long mask = 1ULL << (m-1);
while(mask) {
putchar(show[!!(n&mask)]); mask >>= 1;
}
putchar('\n');
}
Use below function:
void conbin(int num){
if(num != 0)
{
conbin(num >> 1);
if (num & 1){
printf("1");
}
else{
printf("0");
}
}
}
Some runtimes support "%b" although that is not a standard.
Also see here for an interesting discussion:
http://bytes.com/forum/thread591027.html
HTH
This approach has as attributes:
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define for_endian(size) for (int i = 0; i < size; ++i)
#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define for_endian(size) for (int i = size - 1; i >= 0; --i)
#else
#error "Endianness not detected"
#endif
#define printb(value) \
({ \
typeof(value) _v = value; \
__printb((typeof(_v) *) &_v, sizeof(_v)); \
})
void __printb(void *value, size_t size)
{
uint8_t byte;
size_t blen = sizeof(byte) * 8;
uint8_t bits[blen + 1];
bits[blen] = '\0';
for_endian(size) {
byte = ((uint8_t *) value)[i];
memset(bits, '0', blen);
for (int j = 0; byte && j < blen; ++j) {
if (byte & 0x80)
bits[j] = '1';
byte <<= 1;
}
printf("%s ", bits);
}
printf("\n");
}
int main(void)
{
uint8_t c1 = 0xff, c2 = 0x44;
uint8_t c3 = c1 + c2;
printb(c1);
printb((char) 0xff);
printb((short) 0xff);
printb(0xff);
printb(c2);
printb(0x44);
printb(0x4411ff01);
printb((uint16_t) c3);
printf("\n");
return 0;
}
$ ./printb
11111111
11111111
00000000 11111111
00000000 00000000 00000000 11111111
01000100
00000000 00000000 00000000 01000100
01000100 00010001 11111111 00000001
00000000 01000011
I have used another approach (bitprint.h) to fill a table with all bytes (as bit strings) and print them based on the input/index byte. It's worth taking a look.
void DisplayBinary(unsigned int n)
{
int l = sizeof(n) * 8;
for (int i = l - 1 ; i >= 0; i--) {
printf("%x", (n & (1 << i)) >> i);
}
}
void print_ulong_bin(const unsigned long * const var, int bits) {
int i;
#if defined(__LP64__) || defined(_LP64)
if( (bits > 64) || (bits <= 0) )
#else
if( (bits > 32) || (bits <= 0) )
#endif
return;
for(i = 0; i < bits; i++) {
printf("%lu", (*var >> (bits - 1 - i)) & 0x01);
}
}
should work - untested.
Hacky but works for me:
#define BYTE_TO_BINARY_PATTERN "%c%c%c%c%c%c%c%c"
#define BYTE_TO_BINARY(byte) \
(byte & 0x80 ? '1' : '0'), \
(byte & 0x40 ? '1' : '0'), \
(byte & 0x20 ? '1' : '0'), \
(byte & 0x10 ? '1' : '0'), \
(byte & 0x08 ? '1' : '0'), \
(byte & 0x04 ? '1' : '0'), \
(byte & 0x02 ? '1' : '0'), \
(byte & 0x01 ? '1' : '0')
printf("Leading text "BYTE_TO_BINARY_PATTERN, BYTE_TO_BINARY(byte));
For multi-byte types
printf("m: "BYTE_TO_BINARY_PATTERN" "BYTE_TO_BINARY_PATTERN"\n",
BYTE_TO_BINARY(m>>8), BYTE_TO_BINARY(m));
You need all the extra quotes unfortunately. This approach has the efficiency risks of macros (don't pass a function as the argument to BYTE_TO_BINARY) but avoids the memory issues and multiple invocations of strcat in some of the other proposals here.
Even for the runtime libraries that DO support %b it seems it's only for integer values.
If you want to print floating-point values in binary, I wrote some code you can find at http://www.exploringbinary.com/converting-floating-point-numbers-to-binary-strings-in-c/ .
I just want to post my solution. It's used to get zeroes and ones of one byte, but calling this function few times can be used for larger data blocks. I use it for 128 bit or larger structs. You can also modify it to use size_t as input parameter and pointer to data you want to print, so it can be size independent. But it works for me quit well as it is.
void print_binary(unsigned char c)
{
unsigned char i1 = (1 << (sizeof(c)*8-1));
for(; i1; i1 >>= 1)
printf("%d",(c&i1)!=0);
}
void get_binary(unsigned char c, unsigned char bin[])
{
unsigned char i1 = (1 << (sizeof(c)*8-1)), i2=0;
for(; i1; i1>>=1, i2++)
bin[i2] = ((c&i1)!=0);
}
Next will show to you memory layout:
#include <limits>
#include <iostream>
#include <string>
using namespace std;
template<class T> string binary_text(T dec, string byte_separator = " ") {
char* pch = (char*)&dec;
string res;
for (int i = 0; i < sizeof(T); i++) {
for (int j = 1; j < 8; j++) {
res.append(pch[i] & 1 ? "1" : "0");
pch[i] /= 2;
}
res.append(byte_separator);
}
return res;
}
int main() {
cout << binary_text(5) << endl;
cout << binary_text(.1) << endl;
return 0;
}
This code should handle your needs up to 64 bits.
I created two functions: pBin and pBinFill. Both do the same thing, but pBinFill fills in the leading spaces with the fill character provided by its last argument.
The test function generates some test data, then prints it out using the pBinFill function.
#define kDisplayWidth 64
char* pBin(long int x,char *so)
{
char s[kDisplayWidth+1];
int i = kDisplayWidth;
s[i--] = 0x00; // terminate string
do { // fill in array from right to left
s[i--] = (x & 1) ? '1' : '0'; // determine bit
x >>= 1; // shift right 1 bit
} while (x > 0);
i++; // point to last valid character
sprintf(so, "%s", s+i); // stick it in the temp string string
return so;
}
char* pBinFill(long int x, char *so, char fillChar)
{
// fill in array from right to left
char s[kDisplayWidth+1];
int i = kDisplayWidth;
s[i--] = 0x00; // terminate string
do { // fill in array from right to left
s[i--] = (x & 1) ? '1' : '0';
x >>= 1; // shift right 1 bit
} while (x > 0);
while (i >= 0) s[i--] = fillChar; // fill with fillChar
sprintf(so, "%s", s);
return so;
}
void test()
{
char so[kDisplayWidth+1]; // working buffer for pBin
long int val = 1;
do {
printf("%ld =\t\t%#lx =\t\t0b%s\n", val, val, pBinFill(val, so, '0'));
val *= 11; // generate test data
} while (val < 100000000);
}
Output:
00000001 = 0x000001 = 0b00000000000000000000000000000001
00000011 = 0x00000b = 0b00000000000000000000000000001011
00000121 = 0x000079 = 0b00000000000000000000000001111001
00001331 = 0x000533 = 0b00000000000000000000010100110011
00014641 = 0x003931 = 0b00000000000000000011100100110001
00161051 = 0x02751b = 0b00000000000000100111010100011011
01771561 = 0x1b0829 = 0b00000000000110110000100000101001
19487171 = 0x12959c3 = 0b00000001001010010101100111000011
It might be not very efficient but it's quite simple. Try this:
tmp1 = 1;
while(inint/tmp1 > 1) {
tmp1 <<= 1;
}
do {
printf("%d", tmp2=inint/tmp1);
inint -= tmp1*tmp2;
} while((tmp1 >>= 1) > 0);
printf(" ");
Use:
char buffer [33];
itoa(value, buffer, 2);
printf("\nbinary: %s\n", buffer);
For more ref., see How to print binary number via printf.
Is there a printf converter to print in binary format?
The printf() family is only able to print integers in base 8, 10, and 16 using the standard specifiers directly. I suggest creating a function that converts the number to a string per code's particular needs.
To print in any base [2-36]
All other answers so far have at least one of these limitations.
Use static memory for the return buffer. This limits the number of times the function may be used as an argument to printf().
Allocate memory requiring the calling code to free pointers.
Require the calling code to explicitly provide a suitable buffer.
Call printf() directly. This obliges a new function for to fprintf(), sprintf(), vsprintf(), etc.
Use a reduced integer range.
The following has none of the above limitation. It does require C99 or later and use of "%s". It uses a compound literal to provide the buffer space. It has no trouble with multiple calls in a printf().
#include <assert.h>
#include <limits.h>
#define TO_BASE_N (sizeof(unsigned)*CHAR_BIT + 1)
// v. compound literal .v
#define TO_BASE(x, b) my_to_base((char [TO_BASE_N]){""}, (x), (b))
// Tailor the details of the conversion function as needed
// This one does not display unneeded leading zeros
// Use return value, not `buf`
char *my_to_base(char buf[TO_BASE_N], unsigned i, int base) {
assert(base >= 2 && base <= 36);
char *s = &buf[TO_BASE_N - 1];
*s = '\0';
do {
s--;
*s = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[i % base];
i /= base;
} while (i);
// Could employ memmove here to move the used buffer to the beginning
// size_t len = &buf[TO_BASE_N] - s;
// memmove(buf, s, len);
return s;
}
#include <stdio.h>
int main(void) {
int ip1 = 0x01020304;
int ip2 = 0x05060708;
printf("%s %s\n", TO_BASE(ip1, 16), TO_BASE(ip2, 16));
printf("%s %s\n", TO_BASE(ip1, 2), TO_BASE(ip2, 2));
puts(TO_BASE(ip1, 8));
puts(TO_BASE(ip1, 36));
return 0;
}
Output
1020304 5060708
1000000100000001100000100 101000001100000011100001000
100401404
A2F44
Is there a printf converter to print in binary format?
There's no standard printf format specifier to accomplish "binary" output. Here's the alternative I devised when I needed it.
Mine works for any base from 2 to 36. It fans the digits out into the calling frames of recursive invocations, until it reaches a digit smaller than the base. Then it "traverses" backwards, filling the buffer s forwards, and returning. The return value is the size used or -1 if the buffer isn't large enough to hold the string.
int conv_rad (int num, int rad, char *s, int n) {
char *vec = "0123456789" "ABCDEFGHIJKLM" "NOPQRSTUVWXYZ";
int off;
if (n == 0) return 0;
if (num < rad) { *s = vec[num]; return 1; }
off = conv_rad(num/rad, rad, s, n);
if ((off == n) || (off == -1)) return -1;
s[off] = vec[num%rad];
return off+1;
}
One big caveat: This function was designed for use with "Pascal"-style strings which carry their length around. Consequently conv_rad, as written, does not nul-terminate the buffer. For more general C uses, it will probably need a simple wrapper to nul-terminate. Or for printing, just change the assignments to putchar()s.
Maybe someone will find this solution useful:
void print_binary(int number, int num_digits) {
int digit;
for(digit = num_digits - 1; digit >= 0; digit--) {
printf("%c", number & (1 << digit) ? '1' : '0');
}
}
Maybe a bit OT, but if you need this only for debuging to understand or retrace some binary operations you are doing, you might take a look on wcalc (a simple console calculator). With the -b options you get binary output.
e.g.
$ wcalc -b "(256 | 3) & 0xff" = 0b11
My solution:
long unsigned int i;
for(i = 0u; i < sizeof(integer) * CHAR_BIT; i++) {
if(integer & LONG_MIN)
printf("1");
else
printf("0");
integer <<= 1;
}
printf("\n");
The following recursive function might be useful:
void bin(int n)
{
/* Step 1 */
if (n > 1)
bin(n/2);
/* Step 2 */
printf("%d", n % 2);
}
Quick and easy solution:
void printbits(my_integer_type x)
{
for(int i=sizeof(x)<<3; i; i--)
putchar('0'+((x>>(i-1))&1));
}
Works for any size type and for signed and unsigned ints. The '&1' is needed to handle signed ints as the shift may do sign extension.
There are so many ways of doing this. Here's a super simple one for printing 32 bits or n bits from a signed or unsigned 32 bit type (not putting a negative if signed, just printing the actual bits) and no carriage return. Note that i is decremented before the bit shift:
#define printbits_n(x,n) for (int i=n;i;i--,putchar('0'|(x>>i)&1))
#define printbits_32(x) printbits_n(x,32)
What about returning a string with the bits to store or print later? You either can allocate the memory and return it and the user has to free it, or else you return a static string but it will get clobbered if it's called again, or by another thread. Both methods shown:
char *int_to_bitstring_alloc(int x, int count)
{
count = count<1 ? sizeof(x)*8 : count;
char *pstr = malloc(count+1);
for(int i = 0; i<count; i++)
pstr[i] = '0' | ((x>>(count-1-i))&1);
pstr[count]=0;
return pstr;
}
#define BITSIZEOF(x) (sizeof(x)*8)
char *int_to_bitstring_static(int x, int count)
{
static char bitbuf[BITSIZEOF(x)+1];
count = (count<1 || count>BITSIZEOF(x)) ? BITSIZEOF(x) : count;
for(int i = 0; i<count; i++)
bitbuf[i] = '0' | ((x>>(count-1-i))&1);
bitbuf[count]=0;
return bitbuf;
}
Call with:
// memory allocated string returned which needs to be freed
char *pstr = int_to_bitstring_alloc(0x97e50ae6, 17);
printf("bits = 0b%s\n", pstr);
free(pstr);
// no free needed but you need to copy the string to save it somewhere else
char *pstr2 = int_to_bitstring_static(0x97e50ae6, 17);
printf("bits = 0b%s\n", pstr2);
My solution returns an int which can then be used in printf. It can also return the bits in big endian or little endian order.
#include <stdio.h>
#include <stdint.h>
int binary(uint8_t i,int bigEndian)
{
int j=0,m = bigEndian ? 1 : 10000000;
while (i)
{
j+=m*(i%2);
if (bigEndian) m*=10; else m/=10;
i >>= 1;
}
return j;
}
int main()
{
char buf[]="ABCDEF";
printf("\nbig endian = ");
for (int i=0; i<5; i++) printf("%08d ",binary(buf[i],1));
printf("\nwee endian = ");
for (int i=0; i<5; i++) printf("%08d ",binary(buf[i],0));
getchar();
return 0;
}
Outputs
big endian = 01000001 01000010 01000011 01000100 01000101 01000110
wee endian = 10000010 01000010 11000010 00100010 10100010 01100010
Print the least significant bit and shift it out on the right. Doing this until the integer becomes zero prints the binary representation without leading zeros but in reversed order. Using recursion, the order can be corrected quite easily.
#include <stdio.h>
void print_binary(unsigned int number)
{
if (number >> 1) {
print_binary(number >> 1);
}
putc((number & 1) ? '1' : '0', stdout);
}
To me, this is one of the cleanest solutions to the problem. If you like 0b prefix and a trailing new line character, I suggest wrapping the function.
I liked the code by paniq, the static buffer is a good idea. However it fails if you want multiple binary formats in a single printf() because it always returns the same pointer and overwrites the array.
Here's a C style drop-in that rotates pointer on a split buffer.
char *
format_binary(unsigned int x)
{
#define MAXLEN 8 // width of output format
#define MAXCNT 4 // count per printf statement
static char fmtbuf[(MAXLEN+1)*MAXCNT];
static int count = 0;
char *b;
count = count % MAXCNT + 1;
b = &fmtbuf[(MAXLEN+1)*count];
b[MAXLEN] = '\0';
for (int z = 0; z < MAXLEN; z++) { b[MAXLEN-1-z] = ((x>>z) & 0x1) ? '1' : '0'; }
return b;
}
Here's how I did it for an unsigned int
void printb(unsigned int v) {
unsigned int i, s = 1<<((sizeof(v)<<3)-1); // s = only most significant bit at 1
for (i = s; i; i>>=1) printf("%d", v & i || 0 );
}
This is my take on this subject.
Advantages to most other examples:
putchar() which is more efficient than printf() or even (although not as much) puts()Disadvantages to most examples:
print_binary_size() modifies the input variable without a copy.Note: The best outcome for this code relies on using -O1 or higher in gcc or equivalent.
Here's the code:
inline void print_binary_sized(unsigned int number, unsigned int digits) {
static char ZERO = '0';
int digitsLeft = digits;
do{
putchar(ZERO + ((number >> digitsLeft) & 1));
}while(digitsLeft--);
}
void print_binary(unsigned int number) {
int digitsLeft = sizeof(number) * 8;
while((~(number >> digitsLeft) & 1) && digitsLeft){
digitsLeft--;
}
print_binary_sized(number, digitsLeft);
}
Source: Stackoverflow.com