Formatting string to time

This is a discussion on Formatting string to time within the C++ Programming forums, part of the General Programming Boards category; Hi! I have the following problem: I need to make a digital timer. I must have always 4 digits in ...

  1. #1
    Disturbed Boy gustavosserra's Avatar
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    Formatting string to time

    Hi! I have the following problem: I need to make a digital timer. I must have always 4 digits in the format MM:SS. I know the functions width() and fill(), but I do not know how work with them to acchieve what I need.
    For example 1 minute and 2 seconds must be shown as: 01:02, and not 1:2, or 1: 2.
    Any help would be appreciated.
    Nothing more to tell about me...
    Happy day =)

  2. #2
    End Of Line Hammer's Avatar
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    Read here, attempt to write it yourself, then post your code here when you're stuck.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
    Disturbed Boy gustavosserra's Avatar
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    First, thanks for the help! I have created a solution, altough it is slow:
    Code:
          stringstream str;
          str.fill('0');
          str.width(2);
          str << (currentTime-initialTime)/60;
          str << ':';
          str.width(2);
          str << (currentTime-initialTime)%60;
          string str2;
          str >> str2;
          mClock->value(str2.c_str());
    Is there any faster way?
    Nothing more to tell about me...
    Happy day =)

  4. #4
    Registered User
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    How about sticking with cout and avoiding use of stringstreams? Sorry, no compiler handy to test before posting.

    #include<iomanip>

    cout.setiosflags(ios::right);
    cout << setw(2) << setfill('0') <<

    or if you (as some others) prefer, using the format string of printf() to accomplish your needs.

    or even

    if((currentTime-initialTime)/60 < 10)
    cout << '0' << (currentTime-initialTime)/60;
    else
    cout << (currentTime-initialTime)/60;
    Last edited by elad; 05-03-2004 at 08:59 AM.

  5. #5
    Disturbed Boy gustavosserra's Avatar
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    I already tryied printf, but it does not fill with '0'. I need string stream because I do not want to write to the screen. Your option of using if is good, I thought about it, but didn't realize that could get simpler.

    Thanks for the help!
    Nothing more to tell about me...
    Happy day =)

  6. #6
    Been here, done that.
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    Quote Originally Posted by gustavosserra
    I already tryied printf, but it does not fill with '0'. I need string stream because I do not want to write to the screen.
    Then you didn't use it correctly, nor dud you use the proper function.
    Code:
          stringstream str;
          str.fill('0');
          str.width(2);
          str << (currentTime-initialTime)/60;
          str << ':';
          str.width(2);
          str << (currentTime-initialTime)%60;
          string str2;
          str >> str2;
    would become
    Code:
    sprintf(str, "%02d:%02d", (currentTime-initialTime)/60, (currentTime-initialTime)%60);
    Writes to the char buffer str, zero filled.
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  7. #7
    Disturbed Boy gustavosserra's Avatar
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    Thank you so much!!!
    Nothing more to tell about me...
    Happy day =)

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