Char to int using functions

This is a discussion on Char to int using functions within the C++ Programming forums, part of the General Programming Boards category; Hello all, I have a program that imputs some numbers and had 8 different functions that calculate the numbers in ...

  1. #1
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    Char to int using functions

    Hello all,

    I have a program that imputs some numbers and had 8 different functions that calculate the numbers in some sort of way so in the end I have 8 different numbers. I have managed to get all the functions wroking and the number output are right but the last thing I have to do is output the corresponding characters to the integers and I can't seem to work it out. I have tried so many different things. Should I make another function to perform this or just do it in the main? Please help.

    Thanks so much

  2. #2
    C++ Witch laserlight's Avatar
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    Are you trying to convert a char to an int? If so, that is easy, since chars are ints with a limited range. An implicit cast will do:
    Code:
    char ch = 'A';
    int num = ch;
    If you do not want to use a temporary like that, you could always do an explicit cast:
    Code:
    char ch = 'A';
    std::cout << static_cast<int>(ch) << std::endl;
    If you are trying to convert a string to an int, on the other hand, then that needs a little more work, usually by using a stringstream with <sstream>, or atoi() from <cstring>, or perhaps something like Boost's lexical_cast.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    yeah i'm trying to convert a char to an int but the int is a result from a function and for some reason i can't convert it.

    if the number is over 25 i have to number%26 to get a lower number so this is what i have for the function....

    Code:
    char convert (int number)
    {
        char character; 
        if (number >= 25)
          {number = number%26;}
        character = number;
        return character;
    }

  4. #4
    C++ Witch laserlight's Avatar
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    It looks like you are trying to convert an int to a char, but in particular, you are trying to map integers to the alphabet. A simple solution would be something along the lines of:
    Code:
    char convert(int number)
    {
        const char* alphabet = "abcdefghijklmnopqrstuvwxyz";
        return alphabet[number &#37; 26];
    }
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    Thanks so much, it works. Yay!!

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    Just wondering what the * after char does? Why won't it compile without it?
    Thanks

  7. #7
    C++ Witch laserlight's Avatar
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    That is just pointer notation, as in alphabet is a pointer to a null terminated string of characters. Perhaps more C++ish would be:
    Code:
    char convert(int number)
    {
        const std::string alphabet("abcdefghijklmnopqrstuvwxyz");
        return alphabet[number &#37; alphabet.length()];
    }
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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