# Deprecated

This code has been deprecated by the discovery of dtostrf();. See this forum thread, and the avrgcc documentation on stdlib.h

## floatToString

// floatToString.h
//
// Tim Hirzel
// tim@growdown.com
// March 2008
// float to string
//
// If you don't save this as a .h, you will want to remove the default arguments
//     uncomment this first line, and swap it for the next.  I don't think keyword arguments compile in .pde files

//char * floatToString(char * outstr, float value, int places, int minwidth=, bool rightjustify) {
char * floatToString(char * outstr, float value, int places, int minwidth=0, bool rightjustify=false) {
// this is used to write a float value to string, outstr.  oustr is also the return value.
int digit;
float tens = 0.1;
int tenscount = 0;
int i;
float tempfloat = value;
int c = 0;
int charcount = 1;
int extra = 0;
// make sure we round properly. this could use pow from <math.h>, but doesn't seem worth the import
// if this rounding step isn't here, the value  54.321 prints as 54.3209

// calculate rounding term d:   0.5/pow(10,places)
float d = 0.5;
if (value < 0)
d *= -1.0;
// divide by ten for each decimal place
for (i = 0; i < places; i++)
d/= 10.0;
// this small addition, combined with truncation will round our values properly
tempfloat +=  d;

// first get value tens to be the large power of ten less than value
if (value < 0)
tempfloat *= -1.0;
while ((tens * 10.0) <= tempfloat) {
tens *= 10.0;
tenscount += 1;
}

if (tenscount > 0)
charcount += tenscount;
else
charcount += 1;

if (value < 0)
charcount += 1;
charcount += 1 + places;

minwidth += 1; // both count the null final character
if (minwidth > charcount){
extra = minwidth - charcount;
charcount = minwidth;
}

if (extra > 0 and rightjustify) {
for (int i = 0; i< extra; i++) {
outstr[c++] = ' ';
}
}

// write out the negative if needed
if (value < 0)
outstr[c++] = '-';

if (tenscount == 0)
outstr[c++] = '0';

for (i=0; i< tenscount; i++) {
digit = (int) (tempfloat/tens);
itoa(digit, &outstr[c++], 10);
tempfloat = tempfloat - ((float)digit * tens);
tens /= 10.0;
}

// if no places after decimal, stop now and return

// otherwise, write the point and continue on
if (places > 0)
outstr[c++] = '.';

// now write out each decimal place by shifting digits one by one into the ones place and writing the truncated value
for (i = 0; i < places; i++) {
tempfloat *= 10.0;
digit = (int) tempfloat;
itoa(digit, &outstr[c++], 10);
// once written, subtract off that digit
tempfloat = tempfloat - (float) digit;
}
if (extra > 0 and not rightjustify) {
for (int i = 0; i< extra; i++) {
outstr[c++] = ' ';
}
}

outstr[c++] = '\0';
return outstr;
}

## Example Sketch

#include "floatToString.h"  //set to whatever is the location of floatToStrig

void setup() {

Serial.begin(9600);

char buffer[25]; // just give it plenty to write out any values you want to test
// ==========================================
// now run a series on the floatToString function

// looking at the precision of the float

Serial.println("floatToString(buffer, 1000000.321 , 5);");
Serial.println(floatToString(buffer, 1000000.321, 5));
Serial.println();
Serial.println("floatToString(buffer, 100000.321 , 5);");
Serial.println(floatToString(buffer, 100000.321, 5));
Serial.println();
Serial.println("floatToString(buffer, 10000.321 , 5);");
Serial.println(floatToString(buffer, 10000.321, 5));
Serial.println();
Serial.println("floatToString(buffer, 1000.321 , 5);");
Serial.println(floatToString(buffer, 1000.321, 5));
Serial.println();
Serial.println("floatToString(buffer, 100.321 , 5);");
Serial.println(floatToString(buffer, 100.321, 5));
Serial.println();

// ==========================================
// looking at effect of changing precision
Serial.println("floatToString(buffer, 100000.321 , 6);");
Serial.println(floatToString(buffer, 100000.321, 6));
Serial.println();
Serial.println("floatToString(buffer, 100000.321 , 7);");
Serial.println(floatToString(buffer, 100000.321, 7));
Serial.println();
Serial.println("floatToString(buffer, 100000.321 , 8);");
Serial.println(floatToString(buffer, 100000.321, 8));
Serial.println();
Serial.println("floatToString(buffer, 100000.321 , 9);");
Serial.println(floatToString(buffer, 100000.321, 9));
Serial.println();

// ==========================================

// check negatives and rounding, and some edge cases
Serial.println("floatToString(buffer, -5004.321 , 5);");
Serial.println(floatToString(buffer, -5004.321 , 5));
Serial.println();

Serial.println("floatToString(buffer, 99.999 , 3); ");
Serial.println(floatToString(buffer, 99.999 , 3));
Serial.println();

Serial.println("floatToString(buffer, 100, 1);");
Serial.println(floatToString(buffer, 100, 1));
Serial.println();

Serial.println("floatToString(buffer, -100.999 , 1);");
Serial.println(floatToString(buffer, -100.999 , 1));
Serial.println();

Serial.println("floatToString(buffer, -54.321 , 0);");
Serial.println(floatToString(buffer, -54.321 , 0));
Serial.println();

Serial.println("floatToString(buffer, 0.321 , 5);");
Serial.println(floatToString(buffer, 0.321 , 5));
Serial.println();

Serial.println("floatToString(buffer, -1.0001 , 5);");
Serial.println(floatToString(buffer, -1.0001 , 5));
Serial.println();

Serial.println("floatToString(buffer, -0.000001 , 5);");
Serial.println(floatToString(buffer, -0.000001 , 5));
Serial.println();

Serial.println("floatToString(buffer, 0.000001 , 5);");
Serial.println(floatToString(buffer, 0.000001 , 5));
Serial.println();

Serial.println("floatToString(buffer, -0.00001 , 5);");
Serial.println(floatToString(buffer, -0.00001 , 5));
Serial.println();

Serial.println("floatToString(buffer, 0.000099 , 5);");
Serial.println(floatToString(buffer, 0.000099 , 5));
Serial.println();

// alternative technique that depends on <stdio.h>
//Serial.println("Serial.println(dtostrf(-1.0001, 2, 5, s));");
//char s[32];
// Serial.println(dtostrf(-1.0001, 2, 5, s)));

delay(1000);
Serial.println();

}

void loop() {
}