Compile error - Invalid types 'char[int]' for array subscript

Question

I'm working on a program that does some matrix math. Fortunately the code logic is not what is giving me the errors.

I am using the following code to output a matrix that is stored in a 2-d array:

void ouputMatrix(char arr[], int matrixRows, int matrixColumns) {

for (int a=0; a<matrixRows; a++) {
    for (int i=0; i<matrixColumns; i++) {
        cout << arr[a][i] << " ";
    }
    cout << endl;   
}
cout << endl;
}

However when I try to compile this code, I am told:

"In function 'void outputMatrix(char*, int, int)': [Error] Invalid types 'char[int]' for array subscript.

The error type suggests to me that I am missing something obvious with regards to c++ array syntax or something like that but I cannot figure it out. What am I doing wrong?

arr[a] is a char. You cannot do [i] on a char. I guess you meant to pass a 2-D array instead of char arr[] — M.M
– M.M, Commented Nov 26, 2015 at 5:43
Ahh, that's probably my issue. I'll post an answer to this once I figure out the proper syntax. — mc-lunar
– mc-lunar, Commented Nov 26, 2015 at 5:45
It'd help if you post where you define and initialize your matrix — M.M
– M.M, Commented Nov 26, 2015 at 5:48

Gaurav · Accepted Answer · 2015-11-26 06:29:05Z

If you would try to pass a 1-D array to function like this then its perfect what you did, but in case you are trying to pass 2-D array then u need to pass the array with its valid syntax, which is not just like the 1-D

i.e. return_type function_name(dataType arrayName[100],int size)

in case you can also leave the subscripts '[]' as blank for 1-D array ONLY,

but for 2-D array it would be

return_type function_name(dataType arrayName[100][100],int rowSize,int colSize)

however you can also leave the subscripts '[]' to be blank here also but only the 1st [] and 2nd must have to contain some value in it. actually it doesn't matter what value you passed in 2nd subscripts, but some value should has to be there, just pass a value to which your 2-D array would not exceed.

And the syntax will keep going like this for further dimensions of array. Hope this will work for you.

mc-lunar · Accepted Answer · 2015-11-26 05:52:58Z

2

The issue was that I was trying to pass a multidimensional array into the function but used the same syntax as I would for a 1-d array. Since the array has a size of 100 (which isn't something you could know based on my question, sorry...) the correct way to pass it is:

void ouputMatrix(char arr[][100], int matrixRows, int matrixColumns);

answered Nov 26, 2015 at 5:52

mc-lunar

3032 gold badges4 silver badges14 bronze badges

Collectives™ on Stack Overflow

Compile error - Invalid types 'char[int]' for array subscript

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related