intialise 2D arrays??

This is a discussion on intialise 2D arrays?? within the C Programming forums, part of the General Programming Boards category; how do you intialise a 2D array? int array[][] ?? how do we use a 2D array as a parameter ...

  1. #1
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    Unhappy intialise 2D arrays??

    how do you intialise a 2D array?

    int array[][] ??

    how do we use a 2D array as a parameter in function?

    void functionName(int array[][] , int numRows , int numCols)

    or

    void functionName(int array[numRows][numCols])

    ??

    please help

  2. #2
    Confused Magos's Avatar
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    This works fine:
    Code:
    #include <stdio.h>
    #include <conio.h>
    
    const int Width=5;
    const int Height=8;
    
    int MyArray[Width][Height]={0};
    
    void Func(int Array[Width][Height])
    {
       Array[0][0]=12345;
    }
    
    int main()
    {
       Func(MyArray);
       printf("%d", MyArray[0][0]);
       getch();
    }
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  3. #3
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    const int Width=5;
    const int Height=8;

    int MyArray[Width][Height]={0};

    so instead of defining the width and height ourselves

    can we have user define it through scanf ?

  4. #4
    Confused Magos's Avatar
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    Originally posted by Unregistered
    so instead of defining the width and height ourselves

    can we have user define it through scanf ?
    Yes, but not in this way. We must use dynamic allocation (new or malloc).

    Sample (creates an int array with 10 elements):
    Code:
    int NrOfElements=10; //You can make the user input this number
    int* Pointer;
    Pointer = new int[NrOfElements]; //Allocate memory
    if(Pointer!=NULL) //Check to see if allocation was successful
    {
       //Do whatever you want here
       ...
       delete[] Pointer; //You must free the memory before you quit, memory leaks will occur otherwise
    }
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  5. #5
    ATH0 quzah's Avatar
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    Originally posted by Magos

    Yes, but not in this way. We must use dynamic allocation (new or malloc).

    Sample (creates an int array with 10 elements):
    Code:
    int NrOfElements=10; //You can make the user input this number
    int* Pointer;
    Pointer = new int[NrOfElements]; //Allocate memory
    if(Pointer!=NULL) //Check to see if allocation was successful
    {
       //Do whatever you want here
       ...
       delete[] Pointer; //You must free the memory before you quit, memory leaks will occur otherwise
    }
    'new' and 'delete' are C++ keywords and they have no function in C. What you would want to do in C is this:

    Code:
    char **new2DCharArray( int x, int y )
    {
        char **c = NULL;
    
        if( x > 0 && y > 0 ) c = malloc( x * y * sizeof( char ) );
        return c;
    }
    Quzah.
    Hope is the first step on the road to disappointment.

  6. #6
    Confused Magos's Avatar
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    Originally posted by quzah


    'new' and 'delete' are C++ keywords and they have no function in C. What you would want to do in C is this:
    Quzah.
    Oops, this is the C forum, right
    My mistake...
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