converting variable to bits?

hi...

let's say i got a char a = 'A';
and an arry of bool b[8];

how to convert variable a into binary and store it into b[]?

Thanks

A for loop, and use of the >>(shift-right) and &(bitwise-and) operators

can you demostrate with some coding?

Code:

---

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

void printBits(unsigned long val){
    int i, end = sizeof(unsigned long) * 8;
    unsigned long tmp = (ULONG_MAX / 2) + 1;
    for (i=0; i<end; i++){
        if (tmp & val) putc('1', stdout);
        else putc('0', stdout);
        tmp >>= 1;
    }
}

int main(){
    int number = 0;
    char buf[BUFSIZ];

    while (1){
        printf("Please enter a number to convert to binary: ");
        fgets(buf, BUFSIZ, stdin);
        rewind(stdin);
        number = atoi(buf);
        printBits(number);
        printf("\n");
    }
    return 0;

}

---

For example:
num & 1 is true if the 1st bit is 1.
Of course if it isnt true, then the 1st bit is 0.
num = num >> 1 would then bitwise shift num such that the 2nd bit is now the 1st bit.

Excellent code, mitakeet. Except I don't see BUFSIZ declared anywhere. Or is it part of one of the header files?

ok.. my code:

Code:

---

void main()
{
        unsigned char a = 1;
        unsigned char b[8];
        char mask = 1;
        int i;
       
        for(i = 8; i > 0; i--)
        {
                printf("%d", a & mask);
                b[i - 1] = a & mask;
                a >>= 1;
        }

        printf("\n");

        for(i = 0; i < 8; i++)
        {
                if(b[i] == 1)
                {
                        printf("1");
                }
                else
                {
                        printf("0");
                }
        }
}

---

ok... now how do we convert from bits back to the original variable value?

BUFSIZ is declared in <stdio.h> and is typically around 512 bytes.

If you want to put it back together, you |= with the appropriate bit mask.

coding example please....

int value = 0;
int mask1 = 1;
value |= mask1;//now first (lowest order) bit is set

int mask2 = 2
value |= mask2;//now first and second low order bits are set

int mask3 = 4;....

based on my program the bits is store on b[8];
i try:

Code:

---

void main()
{
        unsigned char a = 'a';
        unsigned char c = 0;
        unsigned char b[8];
        char mask = 1;
        int i;
       
        for(i = 8; i > 0; i--)
        {
                printf("%d", a & mask);
                b[i - 1] = a & mask;
                a >>= 1;
        }

        printf("\n");

        for(i = 0; i < 8; i++)
        {
                c |= b[i];
                c <<= 1;

                if(b[i] == 1)
                {
                        printf("1");
                }
                else
                {
                        printf("0");
                }               
        }

        printf("\n%c\n", c);
}

---

but not working......

What does it output?

output:

Code:

---


10000110
01100001
┬

---

Thanks

01100001 is the ASCII code for 'a'.

Quote:

---

Originally Posted by dwks

01100001 is the ASCII code for 'a'.

---

yes... the binary ASCII

Quote:

---

Originally Posted by draggy

coding example please....

---

Read the FAQ on bit shifting. While you're at it, read the FAQ on why void main is wrong.


Quzah.

Quote:

---

Originally Posted by quzah

Read the FAQ on bit shifting. While you're at it, read the FAQ on why void main is wrong.


Quzah.

---

Code:

---

int main()
{
        unsigned char a = 'a';
        unsigned char c = 0;
        unsigned char b[8];
        char mask = 1;
        int i;
       
        for(i = 8; i > 0; i--)
        {
                printf("%d", a & mask);
                b[i - 1] = a & mask;
                a >>= 1;
        }

        printf("\n");

        for(i = 0; i < 8; i++)
        {
                c |= b[i];
                c <<= 1;

                if(b[i] == 1)
                {
                        printf("1");
                }
                else
                {
                        printf("0");
                }               
        }

        printf("\n%c\n", c);

        return 0;
}

---

most important part

Code:

---

c |= b[i]; //means c = c | b[i];
c <<= 1;//means c = c << 1;

---

nothing change still get the same old error result....

Fascinating I'm sure, but what exactly do you expect to get? People sure don't know how to ask people to help them. Picture a conversation with someone:

You: This doesn't work.
Them: That's nice.
You: Fix it.
Them: What's wrong?
You: This doesn't work.

That's all well and good, but how about you actually tell us a bit more. How about we take a different turn in our conversation?

You: This doesn't work.
Them: That's nice.
You: Fix it.
Them: What's wrong?
You: Well I input this, and I'm supposed to get this. But I don't, I get that instead.

See how much better that is? Now you try.


Quzah.

Since I'm such a nice guy, here's a hint:

Quote:

---

most important part

Code:

---

c |= b[i]; //means c = c | b[i];
c <<= 1;//means c = c << 1;

---

---

?uoy naC .tahw tuo erugif etiuq t'nac I .senil owt esoht htiw gnorw gnihtemos evah uoy ,revewoh ,trap tcerroc eht detouq evah ot mees uoY


Quzah.

fixed the problem...


Thanks

Quote:

---

Originally Posted by quzah

Since I'm such a nice guy, here's a hint:?uoy naC .tahw tuo erugif etiuq t'nac I .senil owt esoht htiw gnorw gnihtemos evah uoy ,revewoh ,trap tcerroc eht detouq evah ot mees uoY


Quzah.

---

ahahaha

Interesting way to get your point accross. :p