CODEWITHSUNDEEP
cmalloc
user1171901
user1171901

Reputation: 415

there is no heap in c?

I just started reading The C Programming Language by Brian Kernighan and Dennis Ritchie, and I found this statement:

The language does not define any storage allocation facility other than static definition and the stack discipline provided by the local variables of functions; there is no heap or garbage collection.

So does this mean that it is due to the malloc() function, which returns some memory address from heap, that C enjoys access to the Heap memory? And then must malloc be written in some other language, most probably assembly or B?

This may be a silly doubt, but I have to clear it. Thanks.

Upvotes: 37

Views: 5340

Answers (4)

Ben Zotto
Ben Zotto

Reputation: 71048

The C language itself does not specify directly for a heap or how it should work, but does provide pointers, etc.

malloc and its cousins are part of something called the C Standard Library, and are functions that you link to with any standard implementation of C, and those do provide access to memory that is not static or on the stack. On every platform, the way those functions actually obtain and manage that memory can be different.

C is a long-baked language and library, and now it all appears to be of a piece together. But when K&R were writing that book, that was not so obvious, and that statement is a clarification of what belongs to the syntax of the language itself (versus what is typically provided by the supporting libraries).

Upvotes: 34

Khaled Alshaya
Khaled Alshaya

Reputation: 96879

I think the authors are very precise when they say they are talking about the "language". When you talk about C, you have the language and the standard libraries. In the language itself, there is no dynamic memory allocation facility but the standard library provides those facilities.

Upvotes: 7

Joe
Joe

Reputation: 47649

There is no heap explicitly defined in the language. Implementations, however, do use it for dynamically allocated memory.

See this discussion of various kinds of allocation, including heap:

http://en.wikipedia.org/wiki/C_dynamic_memory_allocation

Upvotes: 3

Rob
Rob

Reputation: 15158

malloc gets memory allocated to it from the kernel of the operating system. All languages do this. This is how the operating system makes sure programs have available space though it does not or may not prevent them, particularly those written in C, from attempting to go beyond any limits.

Upvotes: 2

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