Problem converting from char array to int array.

This is a discussion on Problem converting from char array to int array. within the C Programming forums, part of the General Programming Boards category; I'm using the following code to do so: Code: #include <stdio.h> int main () { int i; char ch[20]="1 2 ...

  1. #1
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    Problem converting from char array to int array.

    I'm using the following code to do so:

    Code:
    #include <stdio.h>
    
    int main ()
    {
    int i;
    char ch[20]="1 2 34 4 56672332432";
    int ch1[20];
    for (i=0; i<20; i++)
    {
          ch1[i]=(int)ch[i]-'0';
    }
    for (i=0; i<20; i++)
    {
          printf ("%d\n ", ch1[i]);
    }
    return 0;
    }
    The problem is I can't an integer more than 9 as it is. For example, the array is reading and converting each char separately, so for example if I want to get 34 form char array into an integer 34, it won't do so. It picks and gives 3 separately and 4 separately.

    What should I do for this problem?

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    Use sscanf instead.

  3. #3
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    Ok, instead of the following code:

    Code:
    for (i=0; i<20; i++)
    {
          ch1[i]=(int)ch[i]-'0';
    }
    I tried the following:

    Code:
    for (i=0; i<20; i++)
    {
    sscanf("%s", ch1);
    }
    and also:

    Code:
    for (i=0; i<20; i++)
    {
    ch1[i] = sscanf("%s", ch);
    }
    But neither works. What would be the proper code?

  4. #4
    C++ Witch laserlight's Avatar
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    Let's clarify what you are trying to do. Are you trying to convert the string "1 2 34 4 56672332432" into a sequence of 5 integers, 1, 2, 34, 4 and 56672332432?
    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

  5. #5
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    String would be: ""1 2 34 4 56"

    I want to read this as an int array of size 5.

  6. #6
    C++ Witch laserlight's Avatar
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    Ah. Okay, one approach is to use a stringstream. The idea is to treat the string as if it were the contents of a file. For example:
    Code:
    #include <iostream>
    #include <string>
    #include <sstream>
    
    int main()
    {
        using namespace std;
        string str = "1 2 34 4 56";
    
        stringstream ss(str);
        int numbers[5];
        for (int i = 0; i < 5; ++i)
        {
            ss >> numbers[i];
        }
    
        for (int i = 0; i < 5; ++i)
        {
            cout << numbers[i] << '\n';
        }
    }
    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

  7. #7
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    This is C++. I'm doing in C.

  8. #8
    C++ Witch laserlight's Avatar
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    Right. This thread has been moved to the C programming forum.
    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

  9. #9
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    oh sorry, I didn't know I was in C++ forum! :s

  10. #10
    and the Hat of Guessing tabstop's Avatar
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    Quote Originally Posted by TheUmer View Post
    Ok, instead of the following code:

    Code:
    for (i=0; i<20; i++)
    {
          ch1[i]=(int)ch[i]-'0';
    }
    I tried the following:

    Code:
    for (i=0; i<20; i++)
    {
    sscanf("%s", ch1);
    }
    and also:

    Code:
    for (i=0; i<20; i++)
    {
    ch1[i] = sscanf("%s", ch);
    }
    But neither works. What would be the proper code?
    Have you used any scan functions before? Have you even bothered to look up sscanf anywhere at all?

  11. #11
    "I Win!" by U. Lose vart's Avatar
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    Code:
    #include <stdio.h>
    
    int main ()
    {
        int count = 0;
        int i;
        char ch[20]="1 2 34 4 56";
        int num[20];
        int poz;
        const char* str = ch;
        while(sscanf(str,"%d%n",&num[count], &poz) == 1)
        {
            count++;
            str += poz;
            if(count == 20) break;
        }
        for (i=0; i<count; i++)
        {
            printf ("%d\n", num[i]);
        }
        return 0;
    }
    Last edited by vart; 03-26-2010 at 11:42 AM.
    To be or not to be == true

  12. #12
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    @vart:

    Thanks a lot. That really worked. I'm highly obliged. Now I can carry on with my assignment.

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