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    Counting Minutes in C++
    I understand the question and what to do, but I cannot get the right answer. Does anyone know what I am doing wrong? 
    int CountingMinutesI(string str) { 

  // code goes here 
  // First create two substrings from the original string by finding the position
  // of the hyphen
  int hyphen = str.find('-');
  string time1 = str.substr(0,hyphen);
  string time2 = str.substr(hyphen+1);
  
  int hour1 = 0;
  int hour2 = 0;
  int minutes1 = 0;
  int minutes2 = 0;
  int totalMinutes = 0;
  
  //Traverse through the first substring to find the total number of minutes that
  //have passed for time #1
  for(int i = 0; i < time1.length(); i++){
    //The number that appears after the colon is the number of minutes
    if(time1[i] == ':'){
      minutes1 = time1[i+1];
    }
    
    //If time is in pm, then the number of hours is increased by 12
    if(time1[i] == 'p'){
      if(time1[0] < 12){
        hour1 = (12 + time1[0]);
      }
      else{
        hour1 = 12;
      }
    }
    
    //If time is in am, then the number of hours remains the same
    else if(time1[i] == 'a'){
      if(time1[0] < 12){
        hour1 = time1[0];
      }
      else{
        hour1 = 0; //12:00 am = 0 minutes (starting point)
      }
    }
  }
  
  
  //Doing exactly the same thing we did with time #1 for time #2
  for(int i = 0 ; i < time2.length(); i++){
    if(time1[i] == ':'){
      minutes2 = time2[i+1];
    }
    
    if(time2[i] == 'p'){
      if(time2[0] < 12){
        hour2 = (12 + time2[0]);
      }
      else{
        hour2 = 12;
      }
    }
    
    else if(time2[i] == 'a'){
      if(time2[0] < 12){
        hour2 = time2[0];
      }
      else{
        hour2 = 0;
      }
    }
  }
  
  //Now that we have collected the amount 
  totalMinutes = (hour2 * 60 + minutes2) - (hour1 * 60 + minutes1);
  if(totalMinutes < 0)
    totalMinutes += 1440;
  return totalMinutes; 
            
}
    Gamer4Life posted this question on 11/28/15 | counting, minutes, cpp
    Answers
  • +
    • 2
  • -
    • Instead of parsing by hand it is better to use nicer and shorter solution: 'istringstream' from <sstream>: 
    int hour1, minutes1;
char sym;
istringstream iss(time1);
time1 >> hour1 >> sym >> minutes1;
// assert(sym == ':')
  • +
    • 1
  • -
    • Read answers in reverse order
  • +
    • 1
  • -
    • Time parsing is wrong. You incorrectly get time from string. First, in code string: 
    minutes1 = time1[i+1];
    you assign character ASCII code ('char' type) to 'int' variable. 
    int a = 1;   // a = 1
int b = '1';  // b = 49
  • +
    • 1
  • -
    • The same mistake in other places: 
    if(time2[0] < 12) { // always false cause digit characters have codes from 48 to 57
    hour2 = (12 + time2[0]);
}
    To convert digit character to integer you can use: 
    int charToInt(char ch) {
   return ch - '0';
}
    Secondly, in the same places you use only one character for hours and minutes. When 'time1' is equal to "10:35": 
    hour1 = charToInt(time1[0]) * 10 + charToInt(time1[1])
  • +
    • 0
  • -
    • Thanks for your help Qlogin, but I had already figured it out, what I did instead was use substrings and then create string streams to have that substring and then send it to the integers.
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