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Question

I am passing one dimensional array as an argument for the function.How to find out the size of array in called function?

Below is the sample code :

# include<stdio.h>
int test( int array[ ] ) {
    //find the size of an array
}
int main() {
    int array[ ] = { 1,2,3,4};
    test( array );
    return 0;
}

Answer

You have two options:

int len_array1(int array[], int n) {
  return n;
}
int len_array2(int array[]) {
  int i;
  for(i=0;array[i]!=-1;++i) {}
  return i;
}
int main() {
  int array1[] = {1,2,3,4};
  int array2[] = {1,2,3,4,-1};
  operate_on_array1(array1,4);
  operate_on_array2(array2);
}

You can either store the length of the array somehow (or keep a point to its end) and pass that around, or you can include a special value at the end of the array which it would not otherwise appear in the values within the array.

Many C-style functions prefer the first option (len_array1), but C-style strings use the second option (the special value being the 0x00 or \0 character).