将数字转换为具有多个参数的字符串

Question

I want to convert a number x of a base n to a string and store it in str . str has the max size of max . In this program I don't want to use any library functions. If I reach the maximum size of the array, the function should return false and the array contents should be undefined.

The prototype of the function looks like this:

bool num2str(int x, char *str, unsigned n, unsigned max);

How would I go about making this work? I'm having trouble understanding the algorithm behind it.

I also need to check the value of n , but I already did that:

bool num2str(int x, char *str, unsigned n, unsigned max)
{
    assert(n >= 2 && n <= 36);
    return true;
}

But that's all I could do. Please help.

Answer 1

Let's take a number in base 10: 123456. Now let's repeatedly apply a modulus and an integer division using the number and base 10:

123456 mod 10 = 6
123456 div 10 = 12345

12345 mod 10 = 5
12345 div 10 = 1234

As you can see, modulus by base extracts the last digit, while integer division by base shifts the number on digit to the right. You can do the same for any base. Hope this hint is enough.