float to string without ftoa

[TeMa_1467596]

I couldn't make ftoa work and I wanted to control the display format and rounding - then I came across this code snippet and adapted it but it's still not quite what I need.

Can someone please help me tweak it to add a significant digit parameter so that I can specify how many digits after the decimal point?

Here is the routine

//*****************************************************************************
// TM convert float to string
// tested and working on PSoC6
//*****************************************************************************
void tmFtoStr(char* p, float x)
{
    int n,i=0,k=0;
    n=(int)x;
    while(n>0)
    {
        x/=10;
        n=(int)x;
        i++;
    }
    *(p+i) = '.';
    x *= 10;
    n = (int)x;
    x = x-n;
    while((n>0)||(i>k))
    {
        if(k == i)
            k++;
        *(p+k)='0'+n;
        x *= 10;
        n = (int)x;
        x = x-n;
        k++;
    }
    /* Null-terminated string */
    *(p+k) = '\0';
}

I call it like this

int main(void) 
{
    float flt1;
    char myString[20]={};
    flt1 = 3.142;
    tmFtoStr(myString, flt1);
    printf("%s\n", myString);
.......
}

but the print out from the above is like this...

3.141999721527

I think I know what to do but I am scared that I'll break it -  I want to add a sigDig parameter so I call it like this...

tmFtoStr(myString, flt1, 3);

and get 3.142 - ideally doing rounding if possible.  Any help would be appreciated.

Also, is the problem above because of the inability of floats to store precisely?

Ted