C4996 c ошибка sprintf

I am working on a UDP socket program in windows visual studio.
I am getting an error for sprintf statement. How to correct it?
My code is:

    for (i = 0; i < 30;i++) //take-off
{
    printf("send AT*REF:take offn");
            sprintf(command, "AT*REF=%d,290718208r", seq++);



    rc = sendto(sd, command, strlen(command) + 1, flags, (struct sockaddr *) &droneAddr, sizeof(droneAddr));
    if (rc<0) {
        printf("%s: can not send datan", argv[0]);
            return(1);
                    }
     }

The errors I am getting are :

Error   1 error C4996: 'sprintf': This function or variable may be unsafe. Consider using sprintf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
Error   1 error LNK2019: unresolved external symbol __imp__bind@12
Error   2 error LNK2019: unresolved external symbol __imp__htonl@4 referenced in function _main 
Error   3 error LNK2019: unresolved external symbol __imp__htons@4
Error   4 error LNK2019: unresolved external symbol __imp__sendto@24
Error   5 error LNK2019: unresolved external symbol __imp__socket@12
Error   6 error LNK2019: unresolved external symbol __imp__gethostbyname@4
Error   7 error LNK1120: 6 unresolved externals 

[error C4996: ‘sprintf’: This function or variable may be unsafe. 】Solution

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2 Августа 2017

Время чтения: 5 минут

#include "stdafx.h"
#include <stdio.h>

int main() {
	int a, b;

	printf("Enter a: ");
	scanf("%d", &a);

	printf("Enter b: ");
	scanf("%d", &b);

	printf("a: %d, b: %dn", a, b);
	return 0;
}

For the specific case of getenv, it is indeed not reentrant or thread safe. As for why Microsoft doesn’t just replace it, you can’t take that interface and make it reentrant (you can almost make it «thread safe» with thread local storage, but it would still not be reentrant).

Even if you just took getenv away altogether, there is still the problem that you have the environ variable which would require some serious compiler level support to make thread safe, since it is just data.

Really, using environment variables for anything other than «setting it up before the process starts or at process start, and only reading from it from that point on» is going to probably end in tears if you have more than one thread. setenv and putenv don’t have a rich enough interface to express something like «set this set of environment variables atomically» and likewise getenv doesn’t have a way to express «read this set of environment variables atomically».

_dupenv_s is somewhat silly in my opinion, because if using that suddenly makes your code safe, it could probably done in a safe way with getenv. _dupenv_s solves a tiny subset of the problems with using environment variables in a multithreaded scenario.

For the specific case of getenv, it is indeed not reentrant or thread safe. As for why Microsoft doesn’t just replace it, you can’t take that interface and make it reentrant (you can almost make it «thread safe» with thread local storage, but it would still not be reentrant).

Even if you just took getenv away altogether, there is still the problem that you have the environ variable which would require some serious compiler level support to make thread safe, since it is just data.

Really, using environment variables for anything other than «setting it up before the process starts or at process start, and only reading from it from that point on» is going to probably end in tears if you have more than one thread. setenv and putenv don’t have a rich enough interface to express something like «set this set of environment variables atomically» and likewise getenv doesn’t have a way to express «read this set of environment variables atomically».

_dupenv_s is somewhat silly in my opinion, because if using that suddenly makes your code safe, it could probably done in a safe way with getenv. _dupenv_s solves a tiny subset of the problems with using environment variables in a multithreaded scenario.