Decimal Time of Day Conversion

Question

Introduction

Time is confusing. Sixty seconds to a minute, sixty minutes to an hour, twenty-four hours to a day (and not to mention that pesky am/pm!).

There's no room for such silliness nowadays, so we've decided to adopt the only sensible alternative: decimal days! That is to say, each day is considered 1 whole unit, and anything shorter is written as a decimal fraction of that day. So, for example: "12:00:00" would be written as "0.5", and "01:23:45" might be written as "0.058159".

Because it will take time to get used to the new system, you are tasked with writing a program that can convert between them in both directions.

Challenge

Write a program in the language of your choice, that given a modern time in the ISO-8601 format of "hh:mm:ss", will return the equivalent decimal fraction unit. Likewise, given a decimal fraction, the program should return the time in the modern format initially specified.

You can make the following assumptions:

• The modern time input and output can range from "00:00:00" to "24:00:00"
• The decimal time input and output can range from "0" to "1", and should be able to accept/output up to at least 5 decimal places (such as "0.12345"). More precision is acceptable
• The program should be able to know which conversion direction to perform based on input
• You cannot use time related functions/libraries

The winner will be determined by the shortest code that accomplishes the criteria. They will be selected in at least 7 decimal day units, or if/when there have been enough submissions.

Examples

Here's a(n intentionally) poorly written piece of JavaScript code to be used as an example:

function decimalDay(hms) {
    var x, h, m, s;
    if (typeof hms === 'string' && hms.indexOf(':') > -1) {
        x = hms.split(':');
        return (x[0] * 3600 + x[1] * 60 + x[2] * 1) / 86400;
    }
    h = Math.floor(hms * 24) % 24;
    m = Math.floor(hms * 1440) % 60;
    s = Math.floor(hms * 86400) % 60;
    return (h > 9 ? '' : '0') + h + ':' + (m > 9 ? '' : '0') + m + ':' + (s > 9 ? '' : '0') + s;
}
decimalDay('02:57:46'); // 0.12344907407407407
decimalDay('23:42:12'); // 0.9876388888888888
decimalDay(0.5); // 12:00:00
decimalDay(0.05816); // 01:23:45

Answer 1

CJam, 58 56 42 bytes

I am sure this is too long and can be golfed a lot. But here goes for starters:

86400q':/:d_,({60bd\/}{~*i60b{s2Ue[}%':*}?

Try it online here

Answer 2

Python 2, 159 150 141 + 2 = 143 Bytes

Straightforward solution, can probably be much shorter. Will work on it.

Added two bytes to account for input needing to be enclosed in "s. Also, Sp3000 pointed out an issue with eval() interpreting octals, and showed a way to shorten formatting, use map() and remove one print.

n=input();i=float;d=864e2
if':'in n:a,b,c=map(i,n.split(':'));o=a/24+b/1440+c/d
else:n=i(n);o=(':%02d'*3%(n*24,n*1440%60,n*d%60))[1:]
print o

Check it out on ideone here.

Answer 3

J, 85 bytes

Results:

T '12:00:00'
0.5

T 0.5
12 0 0

T '12:34:56'
0.524259

T 0.524259
12 34 56

T=:3 :'a=.86400 if.1=#y do.>.(24 60 60#:y*a)else.a%~+/3600 60 1*".y#~#:192 24 3 end.'

Total 85

Answer 4

Javascript (ES6), 116 110 bytes

f=x=>x[0]?([h,m,s]=x.split(':'),+s+m*60+h*3600)/86400:[24,60,60].map(y=>('0'+~~(x*=y)%60).slice(-2)).join(':')


// for snippet demo:
i=prompt();
i=i==+i?+i:i; // convert decimal string to number type
alert(f(i))

Commented:

f=x=>
    x[0] ? // if x is a string (has a defined property at '0')
        ([h, m, s] = x.split(':'), // split into hours, minutes, seconds
        +s + m*60 + h*3600) // calculate number of seconds
        / 86400 // divide by seconds in a day
    : // else
        [24, 60, 60]. // array of hours, minutes, seconds
        map(y=> // map each with function
            ('0' + // prepend with string zero
                ~~(x *= y) // multiply x by y and floor it
                % 60 // get remainder
            ).slice(-2) // get last 2 digits
        ).join(':') // join resulting array with colons

Answer 5

Julia, 152 143 142 bytes

Well, I updated my approach to be less "Julian," as they say, for the sake of golfing. For a better (though less concise) approach, see the revision history.

x->(t=[3600,60,1];d=86400;typeof(x)<:String?dot(int(split(x,":")),t)/d:(x*=d;o="";for i=t q,x=x÷i,x%i;o*=lpad(int(q),2,0)*":"end;o[1:end-1]))

This creates an unnamed function that accepts a string or a 64-bit floating point number and returns a 64-bit floating point number or string, respectively. To call it, give it a name, e.g. f=x->....

Ungolfed + explanation:

function f(x)
    # Construct a vector of the number of seconds in an hour,
    # minute, and second
    t = [3600, 60, 1]

    # Store the number of seconds in 24 hours
    d = 86400

    # Does the type of x inherit from the type String?
    if typeof(x) <: String
        # Compute the total number of observed seconds as the
        # dot product of the time split into a vector with the
        # number of seconds in an hour, minute, and second
        s = dot(int(split(x, ":")), t)

        # Get the proportion of the day by dividing this by
        # the number of seconds in 24 hours
        s / d
    else
        # Convert x to the number of observed seconds
        x *= d

        # Initialize an output string
        o = ""

        # Loop over the number of seconds in each time unit
        for i in t
            # Set q to be the quotient and x to be the remainder
            # from x divided by i
            q, x = divrem(x, i)

            # Append q to o, padded with zeroes as necessary
            o *= lpad(int(q), 2, 0) * ":"
        end

        # o has a trailing :, so return everything up to that
        o[1:end-1]
    end
end

Examples:

julia> f("23:42:12")
0.9876388888888888

julia> f(0.9876388888888888)
"23:42:12"

julia> f(f("23:42:12"))
"23:42:12"

Answer 6

Python 3: 143 Bytes

i,k,l,m=input(),60,86400,float
if'.'in i:i=m(i)*l;m=(3*':%02d'%(i/k/k,i/k%k,i%k))[1:]
else:a,b,c=map(m,i.split(':'));m=(a*k*k+b*k+c)/l
print(m)

Same byte count as the python 2 solution but it seems we took different approaches to the maths.

Answer 7

C, 137 bytes

Full C program. Takes input on stdin and outputs on stdout.

main(c){float a,b;scanf("%f:%f:%d",&a,&b,&c)<3?c=a*86400,printf("%02d:%02d:%02d",c/3600,c/60%60,c%60):printf("%f",a/24+b/1440+c/86400.);}

Ungolfed and commented:

int main() {
    // b is float to save a . on 1440
    float a,b;
    // c is int to implicitly cast floats
    int c;

    // If the input is hh:mm:ss it gets splitted into a, b, c
    // Three arguments are filled, so ret = 3
    // If the input is a float, it gets stored in a
    // scanf stops at the first semicolon and only fills a, so ret = 1
    int ret = scanf("%f:%f:%d", &a, &b, &c);

    if(ret < 3) {
        // Got a float, convert to time
        // c = number of seconds from 00:00:00
        c = a * 86400;
        printf("%02d:%02d:%02d", c/3600, c/60 % 60, c%60);
    }
    else {
        // a = hh, b = mm, c = ss
        // In one day there are:
        // 24 hours
        // 1440 minutes
        // 86400 seconds
        printf("%f", a/24 + b/1440 + c/86400.);
    }
}

Answer 8

PHP, 70 69 bytes

<?=strpos($t=$argv[1],58)?strtotime($t)/86400:date("H:i:s",$t*86400);

takes input from command line argument, prints to STDOUT:

If input contains a colon, convert to unix time and divide by (seconds per day),
else multply numeric value with (seconds per day) and format unix time to hh:mm:ss.

Answer 9

Perl, 109 108 101 + 6 (-plaF: flag) = 107 bytes

$_=$#F?($F[0]*60+$F[1]+$F[2]/60)/1440:sprintf"%02d:%02d:%02d",$h=$_*24,$m=($h-int$h)*60,($m-int$m)*60

Using:

perl -plaF: -e '$_=$#F?($F[0]*60+$F[1]+$F[2]/60)/1440:sprintf"%02d:%02d:%02d",$h=$_*24,$m=($h-int$h)*60,($m-int$m)*60' <<< 01:23:45

Try it on Ideone.

Answer 10

Javascript, 194 192 190 188 bytes

function(z){if(isNaN(z)){x=z.split(':');return x[0]/24+x[1]/1440+x[2]/86400}h=(z*24)|0;h%=24;m=(z*1440)|0;m%=60;s=(z*86400)|0;s%=60;return""+(h>9?'':0)+h+':'+(m>9?'':0)+m+':'+(s>9?'':0)+s}

Answer 11

JavaScript ES6, 98 130 bytes

s=>s==+s?'246060'.replace(/../g,l=>':'+('0'+~~(s*=+l)%60).slice(-2)).slice(1):s.split`:`.reduce((a,b)=>+b+(+a)*60)*1/864e2;f(0.5);

Answer 12

C, 156 152 bytes

I thought it is going to be easy for C. But still ended up quite large. :(

n,m=60;d(char*s){strchr(s,58)?printf("%f",(float)(atoi(s)*m*m+atoi(s+3)*m+atoi(s+6))/m/m/24):printf("%02d:%02d:%02d",(n=atof(s)*m*m*24)/m/m,n/m%m,n%m);}

Test Program:

#include <stdio.h>
#include <stdlib.h>

int n,m=60;
d(char*s)
{
    strchr(s,':') ? 
        printf("%f",(float)(atoi(s)*m*m+atoi(s+3)*m+atoi(s+6))/m/m/24):
        printf("%02d:%02d:%02d",(n=atof(s)*m*m*24)/m/m,n/m%m,n%m);
}

int main()
{
    d("01:23:45");
    printf("\n");
    d("02:57:46");
    printf("\n");
    d("23:42:12");
    printf("\n");
    d("12:00:00");
    printf("\n");
    d("0.5");
    printf("\n");
    d("0.05816");
    printf("\n");
    d("0");
    printf("\n");
    d("1");
    printf("\n");
    return 0;
}

Output:

0.058160
0.123449
0.987639
0.500000
12:00:00
01:23:45
00:00:00
24:00:00

Answer 13

Excel, 178 bytes

=IF(LEFT(A1,2)="0.",TEXT(FLOOR(A1*24,1),"00")&":"&TEXT(MOD(FLOOR(A1*1440,1),60),"00")&":"&TEXT(MOD(FLOOR(A1*86400,1),60),"00"),((LEFT(A1,2)*60+MID(A1,4,2))*60+RIGHT(A1,2))/86400)