Error while trying to initialize array /:

**tmrsgv** · 04-20-2012

Hello,

I have just started learning C as a course i'm taking in univ'.

I need to make and manipulate a matrix (I assumed by using two-dimensional array) but when I try to declare and initialize it gives me a compiler error: "error C2143: syntax error : missing ';' before 'type' "

Now, I know what this error means but I have checked everything and tried to move the declaration around the code and it keeps giving me the same error.

I'm posting part of the code (the user is supposed to input the matrix dimensions which I still have not thought about how to do)

Code:

        {
             int row;
             int col;
            printf ("Please enter the matrix height ( number of rows ) :\n");


            scanf ("%d", &row);
            while (row < 2 || row > 15)
            {
                printf ("Wrong input, the matrix height must be between 2 and 15 - try again :\n");
                scanf ("%d", &row);
            }
            


            printf ("Please enter the matrix width ( number of columns ) :\n");
            scanf ("%d", &col);
            while (col < 2 || col > 15)
            {
                printf ("Wrong input, the matrix width must be between 2 and 15 - try again :\n");
                scanf ("%d", &col);
            }
            int mat [4][5];

As you can see, the array is really not related to any of the code above and is in the correct syntax (I think) and still it gives me the error...

I'll really appreciate any idea...

**Salem** · 04-20-2012

Standard (C89) C doesn't allow you to mix declarations (such as your array) and statements.

If your array is fixed dimensions, then move it to the start of the block.

**tmrsgv** · 04-20-2012

thanks for the fast reply!

The array dimensions are constant until the user wants to change them again (by inputting "row" and "col" again), so how can I get the dimensions from the user if the declaration is on top?

**Abhishek Sp** · 04-20-2012

As for as my knowledge,u can't initialize a variable of any datatype in any part of the program expect at the beginning.
Please do correct me if am wrong .

This should help ypu,

Code:

void main()
{
int row,col,mat[50][50],i,j;
 printf ("Please enter the matrix height ( number of rows ) :\n");
  printf ("Please enter the matrix height ( number of rows ) :\n");
 
 
    scanf ("%d", &row);
    while (row < 2 || row > 15)
    {
        printf ("Wrong input, the matrix height must be between 2 and 15 - try again :\n");
        scanf ("%d", &row);
    }
     
 
 
    printf ("Please enter the matrix width ( number of columns ) :\n");
    scanf ("%d", &col);
    while (col < 2 || col > 15)
    {
        printf ("Wrong input, the matrix width must be between 2 and 15 - try again :\n");
        scanf ("%d", &col);
    }
// Entering Elements inside the Matrix.

for(i=0;i<row;i++)
  for(j=0;j<col;j++)
   scanf("%d",&mat[i][j]);

// Printing the Elements inside the Matrix.

for(i=0;i<row;i++)
{
  for(j=0;j<col;j++)
    matrix("%d\t",mat[i][j]);
  printf("\n") ;
}
getch();
}

~FT

**Salem** · 04-20-2012

Typically, you do this
int **mat;

Then when you know the size

Code:

mat = malloc( row * sizeof(*mat) );
for ( r = 0 ; r < row ; r++ ) {
  mat[r] = malloc( col * sizeof(*mat[r]) );
}

Later still, when you're done

Code:

for ( r = 0 ; r < row ; r++ ) {
  free(mat[r]);
}
free(mat);

**tmrsgv** · 04-21-2012

Although I still cannot use malloc\free functions because it wasn't learnt in class yet, I declared the array on top of the code at maximum dimensions ([15][15]) and I only use the dimension the user inputs.

It works perfectly (in the future i'll be able to use the more elegant functions...

**TexasKid** · 04-21-2012

hehe good luck

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