Is there a way to print the bits without using a loop in C?

Question

Right now, what I do is this:

void print_bits(unsigned int x)
{
    int i;
    for(i=WORD_SIZE-1; i>=0; i--) {
        (x & (1 << i)) ? putchar('1') : putchar('0');
    }
    printf("\n");
}

Also, it would be great to have a solution independent of word size (currently set to 32 in my example).

Answer 1

How about this:

void print2Bits(int a) {
    char* table[] = {
        "00",
        "01",
        "10",
        "11"
    };
    puts(table[a & 3]);
}

void printByte(int a) {
    print2Bits(a >> 6);
    print2Bits(a >> 4);
    print2Bits(a >> 2);
    print2Bits(a);
}

void print32Bits(int a) {
    printByte(a >> 24);
    printByte(a >> 16);
    printByte(a >> 8);
    printByte(a);
}

I think, that's the closes you'll get to writing a binary number without a loop.

Answer 2

You may try itoa. Although it is not in standard C lib, it is available in most C compilers.

void print_bits(int x)
{
    char bits[33];
    itoa(x, bits, 2);
    puts(bits);
}