Algorithms in a Nutshell

Manual Memory Allocation | 51

Patterns and

Domains

Note how the address values are all near one another, signifying that they are co-

located. The address of*main.ar1is drawn from the Heap. In the traditional

computational paradigm, the Stack grows “downward” in memory, while the

Heap grows “upward” as shown in Figure 3-4.

The addresses reveal this behavior since the computation proceeds frommain()to

f( )and the addresses of the variables steadily decrease. If the Stack grows too

large, a program crashes because the memory for the individual stack frames will

overwrite memory that should be safely protected in the heap. When this cross-

over occurs depends upon the hardware platform and the initial memory allocated

for the operating system process.

In Example 3-2, the infinite recursion caused a “Segmentation Fault” at the

393,060threcursive call, after the execution Stack had grown to over 12,577,888

bytes in size.

Table 3-5. Addresses for symbols and variables

f variables Addresses main variables Addresses Global symbols Addresses

f.inner 3221222728 main.argc 3221222796 &f 4195576

f.temp 3221222704 main.argv 3221222784 &main 4195648

f.i 3221222700 main.ar1 3221222776

main.ar2 3221222768

main.i 3221222764

main.j 3221222760

*main.ar1 5246992

*main.ar2 5247136

Figure 3-4. Stack and Heap dynamic behavior

Example 3-2. Code exhibiting infinite recursion

#include <stdio.h>

int f(int n) {

printf (" n %d[%u] \n", n, &n);

return f(n+1);

}

Algorithms in a Nutshell
Algorithms in a Nutshell By Gary Pollice, George T. Heineman, Stanley Selkow ISBN:
9780596516246 Publisher: O'Reilly Media, Inc.

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