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Sizeof is resulting different output for the different function for an array?

+2 votes
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See the following program, sizeof is resulting different output for the different function. Can someone explain this/

#include<stdio.h>

void main()
{
    int arr[]={1,2,3,4,5};
    printf("length: %d\n",sizeof(arr));
    printf("length: %d\n",sizeof(arr)/sizeof(int));
    show(arr);
}

void show(int ar[])
{
   printf("length: %d\n", sizeof(ar));
   printf("length: %d\n", sizeof(ar)/sizeof(int));
}

Output

length: 20
length: 5
length: 4
length: 1
posted May 7, 2015 by anonymous

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1 Answer

+2 votes
 
Best answer

Here size of an integer variable is 4 . In main function, arr is declared as an array and sizeof returns size of an array. Size of an array is equal to (# of element * size of one element). That's why first statement is returning length = 20.

When an array is passed to a function, it is received as an pointer and pointer size is 4 bytes. That's is the reason length = 4 in show function.

answer May 8, 2015 by Harshita
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