Question

In a c programming exercise I am asked to convert an int to char without using the C library.

Any idea how to go about it?

edit: what I mean by int is the built in C/C++ type

Thanks.

Answer 1

Cast it?

char c = (char)i;

Or maybe you meant this?

char c = (char)('0' + i);

I’m sure this isn’t what you mean though… I’m guessing you want to create a string (char array)? If so, then you need to convert it one digit at a time starting with the least significant digit. You can do it recursively, in pseudo-code:

function convertToString(i)
   if i < 10
       return convertDigitToChar(i)
   else
       return convertDigitToString(i / 10) concat convertDigitToChar(i % 10)

Here / is integer division and % is integer modulo. You also need to handle negative numbers. This can be done by checking first if you have a negative number, calling the function on the aboslute value and adding the minus sign if necessary.

In C for performance you would probably implement this with a loop instead of using recursion, and by directly modifying the contents of a character array instead of concatenating strings.