Cant compile Windows Socket in C - c

Question

i've made in my windows desktop, a c socket code, but when i compile, it gives me erros, i dnt know how to proceed, can someone help me? i am working in windows 7, but also tried this same code in windows 10, but i got the same errors, here is the c code, i also tried in c++ but got the same errors, c code below:
#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <string.h>
#pragma comment (lib, "Ws2_32.lib")
#define PORT 5555
#define HOST "192.168.1.30"
#define MAX_L 4096
int main(void){
char bfs[MAX_L], bfr[MAX_L];
int sockfd;
socklen_t sin_size = sizeof(struct sockaddr_in);
struct sockaddr_in target_addr;
struct WSAData wsa;
WSAStartup(MAKEWORD(2,2),&wsa);
sockfd = socket(PF_INET, SOCK_STREAM, 0);
target_addr.sin_port = htons(PORT);
target_addr.sin_family = AF_INET;
target_addr.sin_addr.s_addr = inet_addr(HOST);
connect(sockfd, (struct sockaddr *)&target_addr, sin_size);
while(1){
gets(bfs);
send(sockfd, &bfs, MAX_L, 0);
recv(sockfd, &bfr, MAX_L, 0);
printf("%s\n", bfr);
}
closesocket((SOCKET) sockfd);
WSACleanup();
}
error:
gcc -o csocketcode csocketcode.c -lwinsock2

Answer 1

When calling send() and recv(), DON'T use the & operator to pass your char[] arrays. Arrays decay into pointers, so pass the arrays as-is. send() expects a const char*, and recv() expects a char*, but you are passing them both a char(*)[4096] instead, which is not what the functions want. Let the arrays decay to char* for you.
There are other problems with your code:
missing #include <windows.h>
sockfd is declared as int when it should be SOCKET instead.
gets() is dangerous. Also, you are (potentially) sending more data than gets() actually returns.
your use of printf() is expecting null-terminated data, but recv() does not guarantee a null terminator.
no error handling at all.
Try this instead:
#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <windows.h>
#include <string.h>
#pragma comment (lib, "Ws2_32.lib")
#define PORT 5555
#define HOST "192.168.1.30"
#define MAX_L 4096
int main(void) {
char bfs[MAX_L], bfr[MAX_L];
SOCKET sockfd;
struct sockaddr_in target_addr;
struct WSAData wsa;
int err, num_recvd;
size_t str_len;
err = WSAStartup(MAKEWORD(2,2), &wsa);
if (err != 0) {
fprintf(stderr, "WSAStartup() failed, error %d\n", err);
return -1;
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == INVALID_SOCKET) {
err = WSAGetLastError();
fprintf(stderr, "socket() failed, error %d\n", err);
WSACleanup();
return -1;
}
target_addr.sin_port = htons(PORT);
target_addr.sin_family = AF_INET;
target_addr.sin_addr.s_addr = inet_addr(HOST);
if (connect(sockfd, (struct sockaddr *)&target_addr, sizeof(target_addr)) == SOCKET_ERROR) {
err = WSAGetLastError();
fprintf(stderr, "connect() failed, error %d\n", err);
closesocket(sockfd);
WSACleanup();
return -1;
}
while (fgets(bfs, MAX_L, stdin)) {
str_len = strlen(bfs);
if ((str_len > 0) && (bfs[str_len-1] == '\n')) {
--str_len;
}
if (send(sockfd, bfs, str_len, 0) == SOCKET_ERROR) {
err = WSAGetLastError();
fprintf(stderr, "send() failed, error %d\n", err);
closesocket(sockfd);
WSACleanup();
return -1;
}
num_recvd = recv(sockfd, bfr, MAX_L, 0);
if (num_recvd == SOCKET_ERROR) {
err = WSAGetLastError();
fprintf(stderr, "recv() failed, error %d\n", err);
closesocket(sockfd);
WSACleanup();
return -1;
}
if (num_recvd == 0) {
break;
}
printf("%.*s\n", num_recvd, bfr);
}
closesocket(sockfd);
WSACleanup();
return 0;
}

Answer 2

Your code under gcc compiles but cannot be linked because gcc doesn't recognize
#pragma comment (lib, "Ws2_32.lib")
Add -Werror=unknown-pragmas as compiler flag and you will see error: ignoring pragma comment as compiler message.
So you need to pass Ws2_32 library to link in command line:
gcc -o csocketcode csocketcode.c -lWs2_32
gcc tells you about incompatible pointers type (it is treated as warnings), what is described in Chipster's answer. Fix it.