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Python program to convert time from 12 hour to 24 hour format

  • Difficulty Level : Easy
  • Last Updated : 02 May, 2018

Given a time in 12-hour AM/PM format, convert it to military (24-hour) time.

Note : Midnight is 12:00:00 AM on a 12-hour clock and 00:00:00 on a 24-hour clock. Noon is 12:00:00 PM on 12-hour clock and 12:00:00 on 24-hour clock.

Examples :

Input : 11:21:30 PM
Output : 23:21:30

Input : 12:12:20 AM
Output : 00:12:20

Approach : Whether the time format is 12 hours or not, can be found out by using list slicing. Check if last two elements are PM, then simply add 12 to them. If AM, then don’t add. Remove AM/PM from the updated time.

 
Below is the implementation :






# Python program to convert time
# from 12 hour to 24 hour format
  
# Function to convert the date format
def convert24(str1):
      
    # Checking if last two elements of time
    # is AM and first two elements are 12
    if str1[-2:] == "AM" and str1[:2] == "12":
        return "00" + str1[2:-2]
          
    # remove the AM    
    elif str1[-2:] == "AM":
        return str1[:-2]
      
    # Checking if last two elements of time
    # is PM and first two elements are 12   
    elif str1[-2:] == "PM" and str1[:2] == "12":
        return str1[:-2]
          
    else:
          
        # add 12 to hours and remove PM
        return str(int(str1[:2]) + 12) + str1[2:8]
  
# Driver Code        
print(convert24("08:05:45 PM"))

Output :

20:05:45

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