Free the allocated memory

Question

1.00/5 (2 votes)

See more:

test1.c

struct mode {
unsigned int param1;
unsigned int param2;
char param3[255];
unsigned int param3;
}

void function(int param1,int param2 , char* param3, int paramn) {

  
    struct mode* mode;
    /* Allocate the memory */
    mode = (struct mode*)calloc(1, sizeof(struct mode));

   if (mode == NULL)
        exit(0);

    mode->param1 = param1;
    mode->param2 = param2;
    strcpy(mode->param3, param3);
    mode->paramn = paramn;

   sendtheData(mode)
 }

After sending the data i want to free the allocated memory.In order to avaoid Memory leak

test2.h

struct test2 {
unsigned int param1;
unsigned int param2;
char param3[255];
unsigned int param3;
}

test2.c

static struct test2 *test2 = null;
sendtheData(void *arg)
{
 test2 = (struct test2*)aArg;

}

What I have tried:

sendtheData(mode)
     free(mode)

After free memory it gives me heap error in visual studio

Posted 18-Jul-21 23:23pm

Member 14603643

Updated 21-Jul-21 1:54am

v9

Add a Solution

5 solutions

Solution 1

You can free the data only if the sendtheData function internally makes a copy of it.
Since you didn't post the sendtheData definition I'm sorry we cannot help further.

Posted 18-Jul-21 23:28pm

CPallini

Comments

Member 14603643 19-Jul-21 5:44am

void sendtheData (void * aArg)
{
hs = (struct resphs*)aArg;
}

I have the same structure like mode and this code is in another source file

CPallini 19-Jul-21 5:49am

You see, the function doesn't make a copy, so you are not allowed to free it.
Do you have any documentation of the function?

Member 14603643 19-Jul-21 5:59am

no , these is developed by me so dont have any docs . Can you advice me for the same

CPallini 19-Jul-21 6:06am

Well, it would probably better if you show us the complete code, or, at least, you tell us what are you trying to accomplish.

Solution 2

Use free when you no longer access that memory. A better place would be AFTER sending it.

As CPallini hinted: make a copy in the sendtheData() function, when it sending is asyncron. Than delete that also after sending it as the original memory.

Posted 19-Jul-21 0:48am

KarstenK

Comments

Member 14603643 19-Jul-21 7:57am

What you said i understood but implmentation of sendtheData is in another source file where struct mode is not visible or accessible

KarstenK 19-Jul-21 13:46pm

Then you need to make it visible by including the declaration header. I dont understand how than the sendtheData is working when it doenst know WHAT to send.

Member 14603643 20-Jul-21 2:16am

sendtheData has function parameter as void parameter, and same structure is created in that file so the void pointer is assigned to struct resphs

Solution 4

Where are the declaration for

param3

?

Posted 19-Jul-21 15:48pm

steveb

Comments

Member 14603643 20-Jul-21 2:14am

char buff[255];

steveb 20-Jul-21 7:19am

It is not declared in your code. Also if it is char[] then you cannot use assignment operator. U need to use memcpy on param3

Member 14603643 20-Jul-21 12:03pm

yes i have used strcpy(mode->param3, param3) as these are character array .

Solution 5

If the value you are passing into your function for the parameter

char* param3

is a string that is longer than 255 characters or it is not null terminated then this could be your problem.

I would suggest replacing the line

strcpy(mode->param3, param3);

with

strncpy(mode->param3, param3, 255);
mode->param3[254]='\0'

This will guard against this situation.

Posted 21-Jul-21 1:54am

maj000

Comments

Member 14603643 21-Jul-21 10:26am

will surely check and give the feedback thanks for the valuable feedback. One More Question: logic for test2.c sendtheData(void *Arg) is good or any advice to do it more better

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Greg Utas · Accepted Answer · 2021-07-19T01:19:00

Solution 3

Quote:
After free memory it gives me heap error in visual studio

This could also mean that you're writing into the memory after you successfully free it. It's impossible to tell without seeing all your code, and even then it would probably have to be debugged, which isn't something that anyone here is likely to do for you. In Visual Studio, you can set a "memory watch" on mode after you allocate it, and then see if it changes after you free it. This is described here[^].

Posted 19-Jul-21 1:19am

Greg Utas

Updated 19-Jul-21 1:39am

v3

Comments

Greg Utas 19-Jul-21 13:39pm

Despite some idiot's downvote, this is a possible explanation.

Richard MacCutchan 20-Jul-21 4:18am

Countered.

Greg Utas 20-Jul-21 6:38am

Thanks!