Thread: C to C++ translation help?

  1. #1
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    C to C++ translation help?

    i found this program and i'm more familiar with c++ but this is in c and i just can't figure out how to put it into c++

    Code:
    /* Demonstration of the do…..while loop */
    
        #include <stdio.h>
    
        int main(void)
        {
    
            int value, r_digit;
    
            printf(“Enter a number to be reversed.\n”);
            scanf(“%d”, &value);
    
            do
                {
                    r_digit = value % 10;
                    printf(“%d”, r_digit);
                    value = value / 10;
                } while (value != 0);
    
            printf(“\n”);
    
            return 0;
    
    
        }

  2. #2
    Deathray Engineer MacGyver's Avatar
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    Use cout instead of printf(), cin instead of scanf(), and include iostream instead of stdio.h. Lastly, to be completely portable, I believe main() should accept nothing, not even void. For C, void is preferred.

    So yeah... That's easy.

  3. #3
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    Quote Originally Posted by MacGyver View Post
    Lastly, to be completely portable, I believe main() should accept nothing, not even void.
    Your belief is incorrect. In C++ "int main()" is equivalent to "int main(void)".

    There is also the minor point that no return statement is required from main() in C++: falling off the end is equivalent to returning zero. That is also true in the 1999 C standard but not, IIRC, in the 1989 C standard.

  4. #4
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    Although using void for a function argument is allowed in C++, I believe it's generally considered bad style, since the only reason for it is to avoid the ambiguity caused by C's backwards compatibility with the old K&R function declarations, and those aren't allowed in C++. So to make the code fully C++-like, the void should probably be taken out.

  5. #5
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    Last I checked, "bad style C++" (something some mere mortals will frown upon) is a subjective notion that differs from "invalid C++" (something that, arguably, can be defined objectively by reference to the C++ standard).

    I have seen some C++ style guides (admittedly ones I don't subscribe to) that require functions with no arguments to be declared with a void argument list. One of the reasons, stated in one of those style guides, is that a fair amount of C++ code interfaces to legacy C code.

  6. #6
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    If you want to ignore style (a hugely important part of programming), than why not just leave it with printf and scanf? I mean, <cstdio> has them, so, it's perfectly valid C++. Of course, if you actually want to program in C++, taking out the "void" would be a good idea, along with switching to cin, cout, etc.
    Programming Your Mom. http://www.dandongs.com/

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