• Version: 1.0.3
• Release Date: 2018-10-24

Due to some performance reasons %f is not included in the Arduino's implementation of sprintf(). This library contains a simplified implementation of string formatting functions that support float data type.

• Download the Latest release from gitHub.
• Unzip and modify the Folder name to "StringUtil".
• Paste the modified folder on your library folder (On your Libraries folder inside Sketchbooks or Arduino software).
• Download and Install Time library.
• Restart the Arduino Software

#include <Arduino.h>
#include <StringUtil.h>

using namespace StringUtil;

void setup() {
    Serial.begin(9600);
    while (!Serial);
}

void loop() {
    char buf[256];

    fprintf(Serial, "int=%d padint=%05d\r\n", 123, 123);
    fprintf(Serial, "long=%l padlong=%08l\r\n", 123567, 1234567);
    fprintf(Serial, "str=%s substr=%*s\r\n", "abcde", 2, "abcde");
    fprintf(Serial, "float=%f float2=%.2f float3=%05.2f\r\n", 12.123456, 12.123456, 12.123456);
    fprintf(Serial, "char=%c pointer=%p\r\n", 'A', &buf);
    fprintf(Serial, "date=%F time=%T\r\n");
    fprintf(Serial, "hex=%xd HEX=%Xd\r\n", 127, 127);
#ifdef F
    fprintf(Serial, F("flashString: int=%d padint=%05d\r\n"), 123, 123);
#endif
    sprintf(buf, F("buffer: int=%d padint=%05d\r\n"), 123, 123);
    Serial.println(buf);

    while (1);
}

Results:

int=123 padint=00123
long=123567 padlong=01234567
str=abcde substr=ab
float=12.123456 float2=12.12 float3=00012.12
char=A pointer=07FA
date=1970-00-00 time=00:00:00
hex=7f HEX=7F
flashString: int=123 padint=00123
buffer: int=123 padint=00123

• size_t fprintf(Print &out, const char *fmt, ...)
• size_t sprintf(char *str, const char *fmt, ...)
• size_t vfprintf(Print &out, const char *fmt, va_list &args)
• size_t vsprintf(char *str, const char *fmt, va_list &args)
• size_t fprintf(Print &out, const __FlashStringHelper *fmt, ...)
• size_t sprintf(char *str, const __FlashStringHelper *fmt, ...)
• size_t vfprintf(Print &out, const __FlashStringHelper *fmt, va_list &args)
• size_t vsprintf(char *str, const __FlashStringHelper *fmt, va_list &args)

This library does provide an almost complete implementation of the sprintf function known from the standard c library.

The following formats are supported:

• %%: literal percent sign

• %c: ASCII character represented by the given value

• %[0][width][u][x|X]d: signed/unsigned int number

• %[0][width][u][x|X]l: signed/unsigned long number

• %[0][width][.width]f: floating point value

• %[0][width][u][x|X]z: size_t datatype

• %p: void *

• %s: null-terminated string

• %*s: length and string

• %T: current time 'HH:MM:SS'

• %F: current date 'YYYY-MM-DD'

This library depends on the external library Time, which is found here.

Included on example folder, available on Arduino IDE.

• 1.0.3 (2018-10-25): Fix conflicts with Time.h

• 1.0.2 (2016-01-11): Fix bug with '%Y'

• 1.0.1 (2016-01-10): Add formats: %Y, %M, %D, %H, %m, %S

• 1.0.0 (2016-01-02): Initial version.

• Yoreek