Can const variables be used to define an array's initial size?

[electronics_guy]

Hi all,

What is wrong with the snippet:

const int a=5;
int b[a]={1,2,3,4,5};

The compiler always throws an error with the code above.

What could be the problem? Plz help


Thanks in advance

 

[Venkadesh_M]

you can not use a variable as array size but It may be a macro

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Code C - [expand]
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#define a 5
 
int b[a]={1,2,3,4,5};

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already a is constant by this method you are saving a variable space also....

 

[kripacharya]

Logically it seems that it should work. But i suppose it depends on your compiler how its handled.

You could instead "#define a" if you know what it is at compile time.....

 

[Venkadesh_M]

It is not compiler dependent It is c standard in all the compilers.

 

[errakeshpillai]

Many compilers like GCC will allow to use this, but the array should not be initialized. Its values can be changed/assigned afterwards in the program.

 

[Venkadesh_M]

In ubuntu GCC

​

 

[kripacharya]

It is not compiler dependent It is c standard in all the compilers.

Which C standard are you referring to ? I did not realise that all compilers behaved in exactly the same way..... That would surely obviate the need for any variety in C compilers.

 

[Venkadesh_M]

I have compiled in ubutu GCC as well for more info refer this discussion

https://stackoverflow.com/questions/13645936/variably-modified-array-at-file-scope-in-c