Thread: Arrays as method parameters?

Arrays, when used as parameters to functions, actually change to a pointer to their first element. You may have learned that the name of an array may be used almost like a pointer to its first element. That is to say, it's not a pointer, but it can be referenced as one for some things. As such...

Code:

void somefun( int a1[], int a2[], int a3[] )
{
   ...
}

...
int array1[ X ], array2[ Y ], array3[ Z ];

...
somefun( array1, array2, array3 );

Quzah.

Not exactly. You will need to have some way to know when you've reached the end of the array though. So you might consider passing that along to the function as well.

First you make an array. You have to provide at that time, the size of the array:

Code:

int array[ 5 ];

This makes an array of 5 integers, available to us using indexes zero through four.

We can pass it to a function using its name. If you want to pass one single value of the arrray to a function, you specify that location:

Code:

takesanarray( array );
...
takesanint( array[3] );

Now, you can specify the size of what your function expects for an array, but it doesn't really matter if it's a single dimension array:

Code:

void compilesfine( int array[ 10 ] )
{
    /* do stuff */
}
int main( void )
{
    int array[ 5 ];
    compilesfine( array );
    return 0;
}

This will compile without warnings or errors. The reason is, again, arrays as arguments are actually pointers to their type. So the function doesn't actually take "an array of 10 integers", it takes "a pointer to an int". It doesn't care how many integers I'm really passing it, so long as what it is receiving is an integer pointer.


Quzah.

The & operator is for getting the address of a variable. So, unless you mean to print the address of temp, you shouldn't be using it in your printf statement.

Scattering printf statements is one of the easiest ways to help debug. Just make sure you've got them set up right, so you're printing the right thing.

Quzah.

Check the return value of fscanf to see if the scan fails or not. Initialize temp to something, and print it before the fscanf call, just so you know everything is working fine. Typically I do:

Code:

printf( "Reading from file...\n" );
...call fscanf...
printf( "read: %d\n", data );

Also, unless you have a newline, there's no guarantee that printf will flush the output stream (print anything). So it could just be pending and crash before you see it, or whatever it's doing in your case.

Quzah.

You are just declaring (prototyping) it in main. You aren't actually calling it. To call a function, use its name, parenthesis, and any arguments it needs in those parenthesis. Plus, you haven't actually declared any of the variables you're showing as proposed arguments. So you'll need to do that too.

Look again at my first and second posts.


Quzah.

Define "won't work".

Code:

#include<stdio.h>
void foo( int array[], size_t sz )
{
    size_t x;
    for( x = 0; x < sz; x++ )
        printf( "array[ %d ] is %d\n", x, array[ x ] );
}
int main( void )
{
    int a[ 5 ] = { 5, 10, 3, 88, 0 };
    foo( a, 5 );
    return 0;
}

Quzah.