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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
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  • 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])
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  • 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 == ':')
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  • //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
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    2
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    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 == ':')
    
    
    Qlogin
    answered on 12/03/15
    
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    Read answers in reverse order
    
    Qlogin
    answered on 12/03/15
    
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    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
    
    
    Qlogin
    answered on 12/03/15
    
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    1
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    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])
    
    
    Qlogin
    answered on 12/03/15
    
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    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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  • 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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  • Read answers in reverse order
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  • 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
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