c array

Question

Under which of the following conditions, the size of an one-dimensional array need to be specified ?

a) when initialization is a part of definition

b) when it is a declaration

c) when it is a formal parameter or actual parameter

d) none of the above

Answer 1

Option (d) None of the above is correct.

Because,

When Initialization is a part of declaration then we do not need the size.

In the declaration also we do not need to give the size of array. eg. extern int abc[]; is saying that refer to an global array abc defined in some file. 

Similarly when we use that as formal and actual parameter, we do not have to give the size. It will passed as a separate variable. 

Comments

@Arjun Sir, please verify this.

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The last part is not correct. C compiler by default won't figure out the size of an array passed as an argument to a function. For this reason, we must pass the no. of elements in the array too.

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Absolutely sir. Thanks.

Answer 2

b) when it is a declaration

Comments

@Arjun Sir

Is it mandatory to specify while declaration??

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Sorry. no. If we don't give, it is taken as a pointer.

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thanks

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In case of dynamically allocated array , we can give w/o size while declaration but i am not sure to consider that or not here.

eg

int * a;

a=(int *)malloc(n*sizeof(int));

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yes if it is dynamically allocated , then size is not specified

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@Anurag there is no dynamic array in C.

int * a; //a is a pointer here

a = malloc(...) // a gets a value

we can give

extern int a[];

in C and this is a declaration saying a is an array defined as global in some file.

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@Arjun sir

http://www.geeksforgeeks.org/dynamically-allocate-2d-array-c/

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@srestha there a dynamic array is created using malloc- yes, we can create a dynamic array of memory using C language. But C does not have inbuilt dynamic arrays- all arrays are considered static by the C compiler.