Why is this an issue?
It is possible to declare an array without explicitly specifying its size, but using an explicit size declaration is clearer, and is therefore
preferred.
Noncompliant code example
int arr1 [ ]; // Noncompliant; nothing specified
int arr2 [ ] = { [0] = 1, [12] = 36, [4] = 93 }; // Noncompliant; highest index determines size. May be difficult to spot
int pirate [ ] = { 2, 4, 8, 42, 501, 90210, 7, 1776 }; // Noncompliant; size is implicit, not explicit
Compliant solution
int arr1 [10];
int arr2 [13] = { [0] = 1, [12] = 36, [4] = 93 };
int pirate [10] = { 2, 4, 8, 42, 501, 90210, 7, 1776 }; // Implicitly-assigned size was 8. Desired size was 10.
Resources
- MISRA C:2004, 8.12 - When an array is declared with external linkage, its size shall be stated explicitly or defined implicitly by
initialisation
- MISRA C++:2008, 3-1-3 - When an array is declared, its size shall either be stated explicitly or defined implicitly by initialization
- MISRA C:2012, 8.11 - When an array with external linkage is declared, its size should be explicitely specified
- MISRA C:2012, 9.5 - Where designated initializers are used to initialize an array object the size of the array shall be specified explicitly
- CERT, ARR02-C. - Explicitly specify array bounds, even if implicitly defined by an
initializer
