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An error in allocation

H Matherson

We have an issue with this code


struct foo {
 int NumberOfPointers;

 char *Pointers[1];
} xx;

// Allocate A Block Of Pool With Room For 100 Pointers

myHunkyStuff = malloc( sizeof(long) + 100 * sizeof (char *) );

Can anyone explain?

The H Matherson Crew

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  • 0 in reply to ImPer Westermark

    Apart for an obvious error/typo in the code, the task itself is straightforward:

    
struct foo {
 int NumberOfPointers;

 char *Pointers[1];
} xx;

// Allocate A Block Of Pool With Room For 100 Pointers

myHunkyStuff = malloc( sizeof(xx) + (100-1)*sizeof (char *) );

    You want the size of the overall structure (along with any padding that might be present between NumOfPointers and Pointers) plus an array of the 'extra to the one already in' the structure.

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  • 0 in reply to ImPer Westermark

    Apart for an obvious error/typo in the code, the task itself is straightforward:

    
struct foo {
 int NumberOfPointers;

 char *Pointers[1];
} xx;

// Allocate A Block Of Pool With Room For 100 Pointers

myHunkyStuff = malloc( sizeof(xx) + (100-1)*sizeof (char *) );

    You want the size of the overall structure (along with any padding that might be present between NumOfPointers and Pointers) plus an array of the 'extra to the one already in' the structure.

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