Thread: Variable length arrays

Hello,

I am very new on C programing and have crossed the following error out of which I can get off:

"numbersort1.c", line 22: error #2028: expression must have a constant value
int numbers[size];
The code is:
#include <stdio.h>

Code:

int arraysize=0;
void bubblesortit(int *numbers){
        int arrayposition=0;
        int aux;

        for(arrayposition=sizeof(numbers)/sizeof(int); arrayposition > -1; arrayposition--){
                for(int x=0; x < (arrayposition - 1); x++){
                        if (numbers[x] > numbers[x+1]){
                                aux=numbers[x];
                                numbers[x]=numbers[x+1];
                                numbers[x+1]=aux;
                        }
                }
        }
}

main(const int size){
        printf("Informe o numero de dados a inserir: ");
        scanf("%d", &arraysize)a;
        int numbers[arraysize];
        for(int x=0; x < arraysize; x++){
                printf("Informe o numero para a posicao %d: \n", x+1);
                scanf("%d", &numbers[x]);
        }
        bubblesortit(numbers);
        printf("Os valores informados foram\n");
        for(int x=0; x < arraysize; x++){
                printf("%d", numbers[x]);
        }
}

Can anybody tell me how to set this array variable length to get this gig running?

Note: the intent here is to make it run, I am not looking for best practices as of now.

Thank you

I think your problem is here:

Code:

rrayposition=sizeof(numbers)/sizeof(int)

You can't do this in C, since sizeof(numbers) gives you the size of the pointer rather than the array. if you want to do that, you have to define is as a macro instead, like

Code:

#define ARRAYSIZE(array) sizeof(array)/sizeof(array[0])

of course, I could be wrong cause I'm fairly new too. Also this line

Code:

scanf("%d", &arraysize)a;

What is the a?

Thank you.

The "a" you refer to does not exist on the actual code, it must have been something I typed accidentaly while posting it.

The thing is I need to define the size of the array depending on the number of records the user tell the system it is going to insert on runtime, so the define option would not help me in this case. Ain't there any other approach for this?

Thank you.

Be sure you're compiling in C99 mode (and not, say C++ mode).

i can see that the program u wrote is about a sorting for a variable length of an array so i'll write for u another code could be much easier to u:
#include<stdio.h>
#include<stdlib.h>
void swap(int *a,int *b)
{
int t;
t=*a;
*a=*b;
*b=t;
}
void sort(int *a,int n)
{
int i,j;
for(i=n-2;i>=0;i--)
for(j=0;j<=i;j++)
if(*(a+j)>*(a+(j+1)))
swap((a+j),(a+(j+1)));
}
void print(int *a,n)
{
int i;
for(i=0;i<n;i++)
printf("%d\t",*(a+i));
}
int main()
{
int *array,n;
printf("Enter size of array needed:");
scanf("%d",&n);
array=(int *)malloc(sizeof(int)*n);
if(array!=NULL)
{
int i;
for(i=0;i<n;i++)
{
printf("Enter %d no:");
scanf("%d",&array[i]);
}
sort(array,n);
print(array,n);
return 0;
}
else
printf("Not enough memory");
}

Mostafa - when you're posting code - please use code tags

<< !! Posting Code? Read this First !! >>

sorry i forgot to write it
it should be
"printf("Enter %d no.:",i+1);"
this is like a counter.