Passing an Array as an Argument to a Function in C
I Wrote a Function Containing Array as Argument, and Call It by Passing Value of Array as Follows. Void Arraytest(Int A[]) { // Changed the Array a A[0] = A[0]...
I wrote a function containing array as argument, and call it by passing value of array as follows.
void arraytest(int a[])
{
// changed the array a
a[0] = a[0] + a[1];
a[1] = a[0] - a[1];
a[0] = a[0] - a[1];
}
void main()
{
int arr[] = {1, 2};
printf("%d \t %d", arr[0], arr[1]);
arraytest(arr);
printf("\n After calling fun arr contains: %d\t %d", arr[0], arr[1]);
}
What I found is though I am calling arraytest() function by passing values, the original copy of int arr[] is changed.
Can you please explain why?
11 Answers
When passing an array as a parameter, this
void arraytest(int a[])
means exactly the same as
void arraytest(int *a)
so you are modifying the values in main.
For historical reasons, arrays are not first class citizens and cannot be passed by value.
For passing 2D (or higher multidimensional) arrays instead, see my other answer here: How to pass a multidimensional array to a function in C and C++
Passing 1D arrays as function parameters in C (and C++)
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