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Anything wrong

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  • S Smith

    whereas strcat NEEDS a string (empty or otherwise) to append to. so I'll have to memset everything to 0 or initialize everything to 0 right?

    :beer:

    W Offline
    W Offline
    Waldermort
    wrote on last edited by
    #8

    No. When dealing with string buffers you only need to set the first char/wchar/tchar to 0. char myString[100]; // Is a buffer of 100 chars the a string may be copied into. strcat( myString, "Hello World!" ); // will fail because the buffer is full of junk. // but strcpy( myString, "World!" ); // will work because it doesn't care what is in the buffer myString[0] = 0; // copies an empty string to the buffer strcat( myString, "Hello World!" ); // appends the string to the empty string ( also sets the character after '!' to \0 or NULL. The new string is actually 13 chars because there is a 0 at the end. On another note. You shouldn't be using those string functions. There are safer versions available: strcpy_s( myString, 100, "Hello World!" ); These check to make sure the buffer is large enough for the string Also, you might want to read up on TCHAR and the unicode/ansi string functions TCHAR myString[100]; _tcscpy_s( myString, 100, _T("Hello World!");

    Waldermort

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    • S Smith

      The first yes makes me not to click on the x of this window. Could you please tell me what is wrong with the code before I click on x?

      :beer:

      L Offline
      L Offline
      Luc Pattyn
      wrote on last edited by
      #9

      Smith# wrote:

      char chz[4]={0};

      this buffer is too small, your sprintf statement may generate a minus sign, three digits, a space, and a NULL, that is 6 characters. 60 of these could take up to 301 chars, so char szLogBuff [512]={0}; is sufficiently large, and as others already pointed out, your total initialization is a waste, as each strcat will move the initial terminating NULL backwards. BTW: you could get the correct result with less code, and save some cycles, and never have the bug you had, by having sprintf() fill the final buffer right away; all it takes is a variable pointer as the destination, initialized to szLogBuff, and incremented by the return value of sprintf! :)

      Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

      Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

      CPalliniC 1 Reply Last reply
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      • CPalliniC CPallini

        The code (albeit not beautiful) is correct. With szLogBuf[512]={0}; you actually initialize the whole buffer with 0 (that is '\0'). :)

        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
        [My articles]

        L Offline
        L Offline
        Luc Pattyn
        wrote on last edited by
        #10

        CPallini wrote:

        The code ... is correct.

        :thumbsdown:

        Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

        Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

        CPalliniC 1 Reply Last reply
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        • L Luc Pattyn

          CPallini wrote:

          The code ... is correct.

          :thumbsdown:

          Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

          Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

          CPalliniC Offline
          CPalliniC Offline
          CPallini
          wrote on last edited by
          #11

          It isn't wrong. It isn't elegant nor optimal, but not wrong. I think this is a great achievement, after all. (It's a subliminal suggestion for you: could you please hire the OP?)

          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
          [My articles]

          In testa che avete, signor di Ceprano?

          L 1 Reply Last reply
          0
          • L Luc Pattyn

            Smith# wrote:

            char chz[4]={0};

            this buffer is too small, your sprintf statement may generate a minus sign, three digits, a space, and a NULL, that is 6 characters. 60 of these could take up to 301 chars, so char szLogBuff [512]={0}; is sufficiently large, and as others already pointed out, your total initialization is a waste, as each strcat will move the initial terminating NULL backwards. BTW: you could get the correct result with less code, and save some cycles, and never have the bug you had, by having sprintf() fill the final buffer right away; all it takes is a variable pointer as the destination, initialized to szLogBuff, and incremented by the return value of sprintf! :)

            Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

            Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

            CPalliniC Offline
            CPalliniC Offline
            CPallini
            wrote on last edited by
            #12

            Luc Pattyn wrote:

            your sprintf statement may generate a minus sign

            No, it cannot. ;P

            If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
            This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
            [My articles]

            In testa che avete, signor di Ceprano?

            L 1 Reply Last reply
            0
            • CPalliniC CPallini

              It isn't wrong. It isn't elegant nor optimal, but not wrong. I think this is a great achievement, after all. (It's a subliminal suggestion for you: could you please hire the OP?)

              If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
              This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
              [My articles]

              L Offline
              L Offline
              Luc Pattyn
              wrote on last edited by
              #13

              CPallini wrote:

              It isn't elegant

              true.

              CPallini wrote:

              nor optimal

              true.

              CPallini wrote:

              not wrong

              false. see my reply to OP. :)

              Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

              Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

              CPalliniC 1 Reply Last reply
              0
              • CPalliniC CPallini

                Luc Pattyn wrote:

                your sprintf statement may generate a minus sign

                No, it cannot. ;P

                If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                [My articles]

                L Offline
                L Offline
                Luc Pattyn
                wrote on last edited by
                #14

                from the code snippet I can't tell what the definition of BYTE is, could be signed, could be unsigned; I prepare for the worst. Anyway, it isn't really relevant, the buffer isn't sufficiently large. :)

                Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

                Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

                CPalliniC 1 Reply Last reply
                0
                • L Luc Pattyn

                  CPallini wrote:

                  It isn't elegant

                  true.

                  CPallini wrote:

                  nor optimal

                  true.

                  CPallini wrote:

                  not wrong

                  false. see my reply to OP. :)

                  Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

                  Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

                  CPalliniC Offline
                  CPalliniC Offline
                  CPallini
                  wrote on last edited by
                  #15

                  See my reply[^]. :)

                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                  [My articles]

                  In testa che avete, signor di Ceprano?

                  1 Reply Last reply
                  0
                  • L Luc Pattyn

                    from the code snippet I can't tell what the definition of BYTE is, could be signed, could be unsigned; I prepare for the worst. Anyway, it isn't really relevant, the buffer isn't sufficiently large. :)

                    Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

                    Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

                    CPalliniC Offline
                    CPalliniC Offline
                    CPallini
                    wrote on last edited by
                    #16

                    You didn't read the snippet, did you? (hint: it _s_prints the index, the BYTE part is completely insignificant). :)

                    If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                    [My articles]

                    In testa che avete, signor di Ceprano?

                    L 1 Reply Last reply
                    0
                    • CPalliniC CPallini

                      You didn't read the snippet, did you? (hint: it _s_prints the index, the BYTE part is completely insignificant). :)

                      If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                      This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                      [My articles]

                      L Offline
                      L Offline
                      Luc Pattyn
                      wrote on last edited by
                      #17

                      How silly. So that must be wrong too. :laugh:

                      Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

                      Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

                      CPalliniC 1 Reply Last reply
                      0
                      • L Luc Pattyn

                        How silly. So that must be wrong too. :laugh:

                        Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

                        Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

                        CPalliniC Offline
                        CPalliniC Offline
                        CPallini
                        wrote on last edited by
                        #18

                        :laugh:

                        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                        [My articles]

                        In testa che avete, signor di Ceprano?

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