Question

Question for a C program to convert a decimal number to a binary number

Answer 1

All numbers are stored as binary numbers in a computer; how they're displayed to the user depends on context.

A fairly simple way to get the binary representation is to perform a right shift of N-bits (including zero) and mask (AND-type mask, size should match decimal type size) out the first bit. The resulting decimal number will be equal to the Nth bit and you use a loop to get the entire binary number.

Note that you should go from high to low bits if you are appending (ie. printing, putting in a string, etc) otherwise the result will be reversed.

Nth 0
xxxxxxxxxxx
^
|
This first if appending!

Answer 2

You may want to check out: https://www.khanacademy.org/math/pre-algebra/applying-math-reasoning-topic/alternate-number-bases/v/number-systems-introduction to see how to convert between different number bases.

Answer 3

int decimal = 200, x[10];
//convert dec to bin
for(int i = 0; i<10; i++){
x[i] = decimal%2; //take mod 2 to get remainder
decimal = decimal /2; divide by 2
}

//print bin number
for(int i = 9; i>=0; i--){
printf("%d" x[i]);
}

I didn't run it, but it should work, so let me know if it didn't work

Answer 4

For small enough numbers, you can use `atoi()` to turn a decimal string into an `int` type. Then you can use bit wise operations like `&` and `<<` to get each bit from the `int` and put them into the binary string.