Problem allocating memory.

I'm having a problem with my app, it crashes when I try to allocate some memory. What I use to allocate the memory is

Code:

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entpairs[i].key = (char*) (MAX_ENTITY_KEYLENGTH*sizeof(char));

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entpairs is defined as a entpairs_t

Code:

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typedef struct
{
        char *key;
        char *val;
} entpairs_t;

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and MAX_ENTITY_KEYLENGTH is

Code:

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#define MAX_ENTITY_KEYLENGTH        64

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Is there something wrong with my code?

You aren't allocating anything. All you are doing is a cast of the value:

MAX_ENTITY_KEYLENGTH*sizeof(char)

to char*

That's not allocation. Look up malloc() and calloc()

Quote:

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Originally posted by FillYourBrain
You aren't allocating anything. All you are doing is a cast of the value:

MAX_ENTITY_KEYLENGTH*sizeof(char)

to char*

That's not allocation. Look up malloc() and calloc()

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Haha, I forgot to add the malloc, the line should be

Code:

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entpairs[i].key = (char*) malloc(MAX_ENTITY_KEYLENGTH*sizeof(char));

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THANKS FillYourBrain.

>entpairs[i].key = (char*) malloc(MAX_ENTITY_KEYLENGTH*sizeof(char));
The cast isn't needed for malloc and can hide errors if you forget to include stdlib.h. Also, sizeof ( char ) is redundant as it will always be 1. This would be better:

Code:

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entpairs[i].key = malloc(MAX_ENTITY_KEYLENGTH);

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Of course, an explicit sizeof for char arrays is often used to force the type of the expression to size_t. This is done by overly anal programmers...such as myself. :D The following is the preferred method for doing this as it doesn't rely on the type of pointer you are allocating memory to:

Code:

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entpairs[i].key = malloc(MAX_ENTITY_KEYLENGTH * sizeof *entpairs[i].key);

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Analysis of the allocation statement:

Code:

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entpairs[i].key = (char*) malloc(MAX_ENTITY_KEYLENGTH*sizeof(char));

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In the code above, i don't think there can be anything wrong to the right hand side of the statement. so possible errors in the left hand side of the statement are,

1) value of ' i ' goes out of array bound.

2) If ' i ' isn't out of bound index then is entpairs[i] allocated memory?

-Give more Information about your code.

Thanks

Quote:

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Originally posted by doraiashok
Analysis of the allocation statement:

Code:

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entpairs[i].key = (char*) malloc(MAX_ENTITY_KEYLENGTH*sizeof(char));

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In the code above, i don't think there can be anything wrong to the right hand side of the statement. so possible errors in the left hand side of the statement are,

1) value of ' i ' goes out of array bound.

2) If ' i ' isn't out of bound index then is entpairs[i] allocated memory?

-Give more Information about your code.

Thanks

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The problem is fixed, for some reason I forgot to add the malloc so it wasn't doing anything as FillYourBrain pointed to me. So everything works, thanks anyway.