Floating Point Conversions

[sticilface]

I need to convert numbers entered in a browser (Strings) or sent by MQTT (char array) to a floating point number (double).

I've been trying and failing various ways, but I'm pretty new to C (only since i got hold of the beta for this) so i've failed.

Igrr has said that atof has not been implemented ... this is what is in core_esp8266_noniso.c

float atof_internal(const char* s)
{
  float result = 0;
  return result;
}

atol does work but I'd kinda like the decimals... ( i know i can just enter an integer and then divide...)

Does anyone have any ideas... or fancy giving me a quick patch for this.. I'd try.... infact i spent a few hours on it.. but I'm so new to arrays, pointers, and all this that i just fail....

Cheers

A

[igrr]

You can try this:

double os_atof(const char* s)
{
    double rez = 0, fact = 1;
    while (*s && (*s == ' ' || *s == '\t' || *s == '\r' || *s == '\n'))
        s++;
    if (*s == 0)
        return 0; // can't read

    if (*s == '-')
    {
        s++;
        fact = -1;
    };
    for (int point_seen = 0; *s; s++)
    {
        if (*s == '.')
        {
            point_seen = 1;
            continue;
        };
        int d = *s - '0';
        if (d >= 0 && d <= 9)
        {
            if (point_seen)
                fact /= 10.0;
            rez = rez * 10.0f + (double) d;
        };
    };
    return rez * fact;
}

source

I'm not 100% positive this is LGPL though.

[igrr]

Yeah, and you obviously need to change the function name and change double to float.

[sticilface]

Thanks for the speedy reply.. If I cut and paste that function straight into my sketch, it works perfectly.

I tried what you suggested, changed the name of the function to atof_internal, changed return type to float, -/+ changing internal types to float, and it does not compile...

/Users/amelvin/Downloads/Arduino-espfinal.app/Contents/Java/hardware/tools/esp8266/xtensa-lx106-elf/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld: MQTT-Melvide_-_v1.0.2.cpp.elf section .text' will not fit in regioniram1_0_seg'
/Users/amelvin/Downloads/Arduino-espfinal.app/Contents/Java/hardware/tools/esp8266/xtensa-lx106-elf/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libc.a(lib_a-mallocr.o):(.literal+0x1c): undefined reference to _sbrk_r' /Users/amelvin/Downloads/Arduino-espfinal.app/Contents/Java/hardware/tools/esp8266/xtensa-lx106-elf/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libc.a(lib_a-mallocr.o): In functionmalloc_extend_top':
mallocr.c:(.text+0x5e): undefined reference to _sbrk_r' mallocr.c:(.text+0x127): undefined reference to_sbrk_r'
/Users/amelvin/Downloads/Arduino-espfinal.app/Contents/Java/hardware/tools/esp8266/xtensa-lx106-elf/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libc.a(lib_a-freer.o): In function _malloc_trim_r': mallocr.c:(.text+0x366): undefined reference to_sbrk_r'
mallocr.c:(.text+0x38f): undefined reference to _sbrk_r' /Users/amelvin/Downloads/Arduino-espfinal.app/Contents/Java/hardware/tools/esp8266/xtensa-lx106-elf/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libc.a(lib_a-freer.o):mallocr.c:(.text+0x3a0): more undefined references to_sbrk_r' follow
collect2: error: ld returned 1 exit status
Error compiling.

its out old friend sbrk...

Im happy though as the function works just fine inserted into the sketch. cheers for your help