Convert integer to string without access to libraries
The algorithm is easy to see in English.
Given an integer, e.g. 123
divide by 10 => 123/10. Yielding, result = 12 and remainder = 3
add 30h to 3 and push on stack (adding 30h will convert 3 to ASCII representation)
repeat step 1 until result < 10
add 30h to result and store on stack
the stack contains the number in order of | 1 | 2 | 3 | ...
A look on the web for itoa implementation will give you good examples. Here is one, avoiding to reverse the string at the end. It relies on a static buffer, so take care if you reuse it for different values.
char* itoa(int val, int base){
static char buf[32] = {0};
int i = 30;
for(; val && i ; --i, val /= base)
buf[i] = "0123456789abcdef"[val % base];
return &buf[i+1];
}
fast stab at it: (edited to handle negative numbers)
int n = INT_MIN;
char buffer[50];
int i = 0;
bool isNeg = n<0;
unsigned int n1 = isNeg ? -n : n;
while(n1!=0)
{
buffer[i++] = n1%10+'0';
n1=n1/10;
}
if(isNeg)
buffer[i++] = '-';
buffer[i] = '\0';
for(int t = 0; t < i/2; t++)
{
buffer[t] ^= buffer[i-t-1];
buffer[i-t-1] ^= buffer[t];
buffer[t] ^= buffer[i-t-1];
}
if(n == 0)
{
buffer[0] = '0';
buffer[1] = '\0';
}
printf(buffer);