Geek Answers Handbook

Convert integer to binary in C

I am trying to convert integer 10 to binary number 1010.

This code tries to do this, but I get segfault in strcat ():

int int_to_bin(int k)
{
   char *bin;

   bin = (char *)malloc(sizeof(char));
   while(k>0) {
      strcat(bin, k%2);
      k = k/2;
      bin = (char *)realloc(bin, sizeof(char) * (sizeof(bin)+1));
   }
   bin[sizeof(bin)-1] = '\0';

   return atoi(bin);
}

How to convert an integer to binary in C?

+5
source share
9 answers

If you want to convert a number to another number (not a number to a character string), and you can do it with a small range (from 0 to 1023 for implementations with 32-bit integers), you do not need to add char*to the solution

unsigned int_to_int(unsigned k) {
    if (k == 0) return 0;
    if (k == 1) return 1;                       /* optional */
    return (k % 2) + 10 * int_to_int(k / 2);
}

HalosGhost proposed combining code in one line

unsigned int int_to_int(unsigned int k) {
    return (k == 0 || k == 1 ? k : ((k % 2) + 10 * int_to_int(k / 2)));
}
+12
source

You need to initialize bin, for example.

bin = malloc(1);
bin[0] = '\0';

or use calloc:

bin = calloc(1, 1);

You also have an error:

 bin = (char *)realloc(bin, sizeof(char) * (sizeof(bin)+1));

it should be:

 bin = (char *)realloc(bin, sizeof(char) * (strlen(bin)+1));

(.. strlen, sizeof).

strcat.

, .

0, 1 '0', '1'.

strcat char .

, , , , , (, !):

int int_to_bin(int k)
{
   char *bin;
   int tmp;

   bin = calloc(1, 1);
   while (k > 0)
   {
      bin = realloc(bin, strlen(bin) + 2);
      bin[strlen(bin) - 1] = (k % 2) + '0';
      bin[strlen(bin)] = '\0';
      k = k / 2;
   }
   tmp = atoi(bin);
   free(bin);
   return tmp;
}
+6

itoa , atoi .

unsigned int_to_int(unsigned int k) {
    char buffer[65]; /* any number higher than sizeof(unsigned int)*bits_per_byte(8) */
    return atoi( itoa(k, buffer, 2) );
}
+4

, ...

, : "pmg" .

unsigned int int_to_int(unsigned int k) {
    return (k == 0 || k == 1 ? k : ((k % 2) + 10 * int_to_int(k / 2)));
}

: . . , :

 dec 255  -> hex 0xFF  -> bin 0b1111_1111
 dec 1023 -> hex 0x3FF -> bin 0b11_1111_1111

, .

, 

unsigned int_to_int(unsigned int k) {
    char buffer[65]; // any number higher than sizeof(unsigned int)*bits_per_byte(8)
    return itoa( atoi(k, buffer, 2) );
}

. , , , . . , , .

itoa()

char buffer[65];
itoa(k, buffer, 2);
+2

this char* :

   char* itob(int i) {
      static char bits[8] = {'0','0','0','0','0','0','0','0'};
      int bits_index = 7;
      while ( i > 0 ) {
         bits[bits_index--] = (i & 1) + '0';
         i = ( i >> 1);
      }
      return bits;
   }

, printf("%s", itob(170)), 01010101, , 170 . atoi(itob(170)), , 170 .

+1

.

int main()
{
    int num=241; //Assuming 16 bit integer
    for(int i=15; i>=0; i--) cout<<((num >> i) & 1);
    cout<<endl;
    for(int i=0; i<16; i++) cout<<((num >> i) & 1);
    cout<<endl;
    return 0;
}

cout < , .

+1

.

    int* num_to_bit(int a, int *len){
        int arrayLen=0,i=1;
        while (i<a){
            arrayLen++;
            i*=2;
        }
        *len=arrayLen;
        int *bits;
        bits=(int*)malloc(arrayLen*sizeof(int));
        arrayLen--;
        while(a>0){
            bits[arrayLen--]=a&1;
            a>>=1;
        }
        return bits;
     }
0
void intToBin(int digit) {
    int b;
    int k = 0;
    char *bits;

    bits= (char *) malloc(sizeof(char));
    printf("intToBin\n");
    while (digit) {
        b = digit % 2;
        digit = digit / 2;
        bits[k] = b;
        k++;

        printf("%d", b);
    }
    printf("\n");
    for (int i = k - 1; i >= 0; i--) {
        printf("%d", bits[i]);

    }

}
0
short a;
short b;
short c;
short d;
short e;
short f;
short g;
short h;
int i;
char j[256];

printf("BINARY CONVERTER\n\n\n");

//uses <stdlib.h>

while(1)
{

a=0;
b=0;
c=0;
d=0;
e=0;
f=0;
g=0;
h=0;
i=0;


gets(j);
i=atoi(j);
if(i>255){
printf("int i must not pass the value 255.\n");
i=0;
}
if(i>=128){
a=1;
i=i-128;}
if(i>=64){
b=1;
i=i-64;}
if(i>=32){
c=1;
i=i-32;}
if(i>=16){
d=1;
i=i-16;}
if(i>=8){
e=1;
i=i-8;}
if(i>=4){
f=1;
i=i-4;}
if(i>=2){
g=1;
i=i-2;}
if(i>=1){
h=1;
i=i-1;}

printf("\n%d%d%d%d%d%d%d%d\n\n",a,b,c,d,e,f,g,h);
}
-4

More articles:


All Articles