File content as of revision 0:64c04c367702:

// C program for implementation of ftoa()
#include "mbed.h"
#include<stdio.h>
#include<math.h>
Serial pc(USBTX,USBRX); 
// reverses a string 'str' of length 'len'
// driver program to test above funtion


void reverse(char *str, int len)
{
    int i=0, j=len-1, temp;
    while (i<j)
    {
        temp = str[i];
        str[i] = str[j];
        str[j] = temp;
        i++; j--;
    }
}
 
 // Converts a given integer x to string str[].  d is the number
 // of digits required in output. If d is more than the number
 // of digits in x, then 0s are added at the beginning.
int intToStr(int x, char str[], int d)
{
    int i = 0;
    while (x)
    {
        str[i++] = (x%10) + '0';
        x = x/10;
    }
 
    // If number of digits required is more, then
    // add 0s at the beginning
    while (i < d)
        str[i++] = '0';
 
    reverse(str, i);
    str[i] = '\0';
    return i;
}
 
// Converts a floating point number to string.
void ftoa(float n, char *res, int afterpoint)
{
    // Extract integer part
    int ipart = (int)n;
 
    // Extract floating part
    float fpart = n - (float)ipart;
 
    // convert integer part to string
    int i = intToStr(ipart, res, 0);
 
    // check for display option after point
    if (afterpoint != 0)
    {
        res[i] = '.';  // add dot
 
        // Get the value of fraction part upto given no.
        // of points after dot. The third parameter is needed
        // to handle cases like 233.007
        float fp=10;
        fpart =fpart * pow(fp,afterpoint);
        
        intToStr((int)fpart, res + i + 1, afterpoint);
    }
}

int main()
{
    char res[20];
    float n = 233.007;
    ftoa(n, res, 4);
    pc.printf("\n\"%s\"\n", res);
    return 0;
}