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Time Conversion

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  • AbhishekVermaIIT + 20 comments

    For people interested in C, a simple elegant solution with low complexity :

    int main() {
    int hh, mm, ss ;
    char t12[3];
    scanf("%d:%d:%d%s", &hh, &mm, &ss, t12) ;
        
    if (strcmp(t12,"PM")==0 && hh!=12) hh += 12 ;
    if (strcmp(t12,"AM")==0 && hh==12) hh = 0 ;
        
    printf("%02d:%02d:%02d", hh, mm, ss) ;
    return 0;
}

    • Andyuriarte + 3 comments

      the seconds are not displaying properly. Scanf isnt storing the input into ss.

      • AbhishekVermaIIT + 1 comment

        The variable 'ss' is similar to 'mm' or 'hh'. If others are getting displayed, it should also work well. Please recheck code, there might be any minor mistake. Else, post your submission link (or code) here, someone would be able to help for sure after looking at the code.

      • shubham_marathia + 1 comment

        try adding 0 before %2d , that is , do %0d in your printf statement.

        • Andyuriarte + 1 comment

          I think its an issue with the version of C I am using or the compiler. The code executes fine when submitted through Hackerrank. However, on my own machine, it seems that SS is stored as 00 if scanf contains %d%s for the last input. It works fine if you get rid of the string. Strange.

      • RohanSingh + 2 comments

        @Andyuriarte

        There is no problem with the code. The problem is because of the underlying architecture on which your compiler is running. I tried it on windows, it gives correct result but gives wrong answer on linux. See this http://ideone.com/EV58mh

        Here 'time' is stored before 'hour'. Same is happenning in your case and you are not getting correct value for ss.

        • sagemode + 2 comments

          I feel like this solution is not complete. We can't change how the underlying system works now, so I think it is programmers responsibility to consider all these situations into account and write an effective solution.

        • erichamion + 1 comment

          Actually, there is a problem with the code. The line char t12[2]; in the original post doesn't allocate enough space. The string "PM" requires three bytes: 'P', 'M', and a null (zero) byte to end the string. When the machine writes three bytes into a two-byte space, that final null byte is stomping over memory that doesn't belong to the t12 variable. What happens then is very hard to predict, dependent on the implementation and other factors.

          The quick fix would be to correctly declare t12 as char t12[3];.

    • rakeshsingh15 + 1 comment

      Can't i use gets() to provide input to string...

      • AbhishekVermaIIT + 0 comments

        Yeah, you can definitely use gets(). I used scanf() because it made this particular problem a lot easier.


        Though, it depends a lot on the requirement, in general, I would suggest you to never use gets(). It's use is highly discouraged due to no protection to buffer overflow.

        You get strong formatting features with scanf(), but its difficult (although possible) to use it properly with string buffers and impossible to be used safely for arithmetic input. Also, there can be failed scan or trailing newline in case input isn't well formatted. Hence, use scanf() only if you are completely aware of its functionality and know what you are doing (not recommended for new coders).

        Use fgets(). It lets you specify buffer size. Just remember to remove trailing newLine (this also ensures buffer overflow protection).

        In short, use fgets(), avoid scanf() and never use gets().


        For this particular problem, you can use fgets() and pass it to sscanf() for scanf() like behavior, in case, you want to avoid scanf().

    • leo_12345 + 1 comment

      why are you using %02d in outputs instead of %d?

      • AbhishekVermaIIT + 1 comment

        It's for specified output format. %2d will output in 2 digits format and %02d will left pad the result with '0'.

           Format      Data      Result
    %d:%d      11,5      11:5
  %2d:%2d      11,5      11: 5
%02d:%02d      11,5      11:05

        • leo_12345 + 1 comment

          is it like defining the set width ??

  • ankitkraman + 0 comments

    I tried to keep it short and simple so took help of another standard library iomanip and make it simple.. Please don't forget to upvote if you like the solution..

    #include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <iomanip>
using namespace std;

int main(){
    int h, m, s;
    char ch, aorp;
    
    cin >> h >> ch >> m >> ch >> s >> aorp >> ch;
    h = (aorp == 'A') ? (h==12 ? 0 : h) : (h==12 ? 12 : h+12);
        
    cout << setw(2) << setfill('0') << h << ":" 
         << setw(2) << setfill('0') << m << ":" 
         << setw(2) << setfill('0') << s << endl;
    
    return 0;
}

  • Norman99 + 0 comments

    Python solution.

    time = input().strip()
h, m, s = map(int, time[:-2].split(':'))
p = time[-2:]
h = h % 12 + (p.upper() == 'PM') * 12
print(('%02d:%02d:%02d') % (h, m, s))

  • Jashin + 0 comments

    My Java Code after 4hrs of research xD

    public static void main(String[] args) {
        
		Scanner scan = new Scanner(System.in);
        String time = scan.next();
        String tArr[] = time.split(":");
        String AmPm = tArr[2].substring(2,4);
        int hh,mm,ss;
        hh = Integer.parseInt(tArr[0]);
        mm = Integer.parseInt(tArr[1]);
        ss = Integer.parseInt(tArr[2].substring(0,2));
        
        String checkPM = "PM",checkAM ="AM";
        int h = hh;
        if(AmPm.equals(checkAM) && hh==12)
        	h=0;
        else if(AmPm.equals(checkPM)&& hh<12)
        	h+=12;
        
        System.out.printf("%02d:%02d:%02d",h,mm,ss);
    }

  • saswat_nayak_m21 + 0 comments

    It seems test case# 4 doesn't validate. I am getting the exact output as the expected output for test case# 4, however, still not sure why it does not validate. Test Case# 4: input : 04:59:59PM Desired output : 16:59:59

    Output of my code for this test case : 16:59:59

    Not sure, whats going wrong !

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