Why array index in C starts with 0?

The array index in C starts with 0 because in C the name of an array is a pointer, which is a reference to a memory location. Therefore, an expression *(arr + n) or arr[n] locates an element n-locations away from the starting location because the index is used as an offset. Likewise, the first element of the array is exactly contained by the memory location that array refers (0 elements away), so it should be denoted as *(arr + 0) or *(arr) or arr[0].

C programming language has been designed this way, so indexing from 0 is inherent to the language.

However, some languages give user a choice to start index from zero or any other positive integer. For an example, in Fortran, when an array is declared with integer a(10) (an array of 10 integer elements), the index starts from 1 and ends at 10. However, this behavior can be overridden using a statement like, integer a(0:9), declaring an array with indices from 0 to 9.

Hope you have enjoyed reading why array index in C starts with zero? Please do write us if you have any suggestion/comment or come across any error on this page. Thanks for reading!




Get Free Tutorials by Email

About the Author

is the main author for cs-fundamentals.com. He is a software professional (post graduated from BITS-Pilani) and loves writing technical articles on programming and data structures.

Today's Tech News

WannaCry ransom notice analysis suggests Chinese linkPosted on Monday May 29, 2017

Researchers say the WannaCry ransom note was poorly translated - possibly using Google Translate.

BA boss 'won't resign' over flight chaosPosted on Monday May 29, 2017

Chief executive Alex Cruz says flight disruption at Heathrow and Gatwick had nothing to do with cost cutting.

Hay Festival 2017: Stephen Fry's warning for the webPosted on Sunday May 28, 2017

Delivering a lecture at the Hay Festival, the actor said society could face "dire consequences".

Courtesy BBC News