在C中写一个2位数的整数，仅包括<unistd.h>

Question

Assuming I don't have access to any C standard libraries I'm trying to print a 2 digit int using the write(x, x, x) function. I have only included <unistd.h> as per specifications. My current function gives me only the ASCII representation of the value I pass into it.

void my_print(int x)
{
  write(1, &x, 2);
}

Answer 1

Use mod % and div to get upper and lower digit

int low = x%10;
int high = x/10; // could also have a sanity check for the range here

Then transform it to ascii by adding '0' 0x30 and write

putchar(high+'0'); // Let compiler transform to char 
putchar(low+0x30); // Or this if you trust magic constants more

From here it is easy to transform the code to use write function

#include <unistd.h>

void myprint(int x){
   char buf[]= {'0'+(x/10)%10, '0'+x%10};
   write(1,buf,2);
}