Programming Questions

• Popular Tags
• 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 |
• +
• 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]) ```
• +
• 1
• -
• 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 == ':') ```
• +
• 0
• -
• 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 ```
• +
• 0
• -
• +
• 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.
• +
• 0
• -
• ```//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;

}

Gamer4Life posted this question on 11/28/15 | counting, minutes, cpp
+
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
-

+
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])