problem with data in allocated memory

hi,

i have a problem in storing the data in allocated memory using malloc.

i have structure to store huge data form the serial port.

Code:

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typedef struct FileData {               
                unsigned char  *FRdata;
                struct FileData *next;
}FileData;

/*I store the data in FileData->FRdata, by allocating sufficient memory to it*/

Datacur->FRdata=(char *)malloc(sizeof(max_bytes));

for(j=0;bytes_to_read>0;j++,bytes_to_read--)
        Datacur->FRdata[j]=*Ftemp++;
Datacur->next=NULL;

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i have to write the raw data from the serial port in to file after converting the raw into its format[ the data format is usually float type].

when i print few data before opening a file

Code:

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j=0;
printf("read");
while(j<10){
printf("%02x ",Datahead->FRdata[j++]);
}

---

there is no change in the data .

The problem is after , file is opened

Code:

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fptr=fopen(Surveyname,"wt");

---

the data in the allocated memory{Datahead->FRdata[} has changed { the data that is written to file is different to that of original data.}

where cud be the malicious alteration hapened.

any help on this.

Quote:

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where cud be the malicious alteration hapened.

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In what way is it different?

By the way, there is no need to cast the return value of malloc() in C.

Quote:

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Code:

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Datacur->FRdata=(char *)malloc(sizeof(max_bytes));

---

---

You probably don't want a sizeof in there. You probably want just:

Code:

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Datacur->FRdata = malloc(max_bytes);

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How silly i was :D!!!!!! Thanks iMalc for rightly pointing it out......

problem got fixed!!