Thread: Scan and print an array in separate functions? (problem with code)

I'm learning about arrays and functions for a school assignment, so i wrote a test program to check if i understood the theory, but when i print the array the output is wrong.

I just started learning and i honestly have no idea what i'm doing wrong.

Code:

#include <stdio.h>


#define TAMF 2
#define TAMC 3
void scanArray(int array[][]);
void printArray(int array[][]);


int main()
{
    int array[TAMF][TAMC];
    scanArray(array);
    printArray(array);
}


void scanArray(int array[][])
{
    int i,j;
    for(i=0; i<TAMF;i++) {
        for(j=0;j<TAMC;j++){
            printf("Input array[%d][%d]:\n>", i, j);
            scanf("%d", &array[i][j]);
        }
    }
}


void printArray(int array[][])
{
    printf("\n------array------\n");
    int i,j;
    for(i=0; i<TAMF;i++){
        for(j=0;j<TAMC;j++){
            printf("%d\t",array[i][j]);
        }
        printf("\n");
    }
}

For example, if i input:
1 2 3 4 5 6

It outputs:
4 5 6
4 5 6

How does your code even compile? Because It shouldn't. You can't pass a 2D array to a function without telling it its dimensions. All but the leftmost dimension must be passed, like this:

Code:

void scanArray(int array[][TAMC]);
void printArray(int array[][TAMC]);

Originally Posted by GReaper

How does your code even compile? Because It shouldn't. You can't pass a 2D array to a function without telling it its dimensions. All but the leftmost dimension must be passed, like this:

Code:

void scanArray(int array[][TAMC]);
void printArray(int array[][TAMC]);

Complementing GReaper information, here's a brief explanation on why incomplete arrays must have its "lower" dimensions specified. When you declare a complete array like:

Code:

int array[3][4];   // array[dx][dy];

The compiler allocates 12 integers (3*4), sequentially. The 'array' identifier "points" to the first element (array[0][0]), and when you use "[]" operator, this calculation will be done:

Code:

int x = array[2][3];  // example reading array[2][3];
int *p = (int *)array + 4*2 + 3;
int y = *p;  // same thing

Notice the lower dimension is used to place the correct offset as in:

Code:

ptr + dy*x + y

Where "dy" is the lower dimension... Without the lower dimension, the compiler has no clue about each "line" size...

I'm still just blindly coding by trial and error

me too...