I compiled both client and server code using the following commands:

server : gcc server.c -o server.exe -lws2_32
client : gcc client.c -o client.exe -lws2_32

Both codes are successfully complied and generate the .exe files w.r.t the server.c and client.c files.

My problem is, when I run the server.exe file, it opens and suddenly closes automatically.

This is happening also with the client.exe.

Why is that?

server.c:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#define SIZE 1024
void write_file(int sockfd){
    int n;
    FILE *fp;
    char *filename = "file2.txt";
    char buffer[SIZE];
    fp = fopen(filename, "w");
    if(fp==NULL){
        perror("[-]Error in creating file.");
        exit(1);
    }while(1){
        n = recv(sockfd, buffer, SIZE, 0);
        if(n<=0){
            break;
            return;
        }
        fprintf(fp, "%s", buffer);
        memset(buffer, 0, SIZE);
    }
    return;
}

int main (){
    char *ip = "127.0.0.1";
    int port = 8080;
    int e;
    int sockfd, new_sock;
    struct sockaddr_in server_addr, new_addr;
    int addr_size;
    char buffer[SIZE];
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd<0){
        perror("[-]Error in socket");
        exit(1);
    }
     printf("[+]Server socket created. \n");
     server_addr.sin_family = AF_INET;
     server_addr.sin_port = port;
     server_addr.sin_addr.s_addr = inet_addr(ip);
     e = bind(sockfd,(struct sockaddr*)&server_addr, sizeof(server_addr));
     if(e<0){
         perror("[-]Error in Binding");
         exit(1);
     }
     printf("[+]Binding Successful.\n");
     e = listen(sockfd, 10);
     if(e==0){
         printf("[+]Listening...\n");
     }
     else{
         perror("[-]Error in Binding");
         exit(1);
     }
     addr_size = sizeof(new_addr);
     new_sock = accept(sockfd,(struct sockaddr*)&new_addr, &addr_size);
     write_file(new_sock);
     printf("[+]Data written in the text file ");
     return 0;
}

client.c:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <winsock2.h>
#define SIZE 1024
void send_file(FILE *fp, int sockfd){
    char data[SIZE] = {0};
    while(fgets(data, SIZE, fp)!=NULL){
        if(send(sockfd, data, sizeof(data), 0)== -1){
            perror("[-] Error in sending data");
            exit(1);
        }
        memset(data, 0, SIZE);
    }
}
int main(){
    char *ip = "127.0.0.1";
    int port = 8080;
    int e;
    int sockfd;
    struct sockaddr_in server_addr;
    FILE *fp;
    char *filename = "file.txt";
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd<0){
        perror("[-]Error in socket");
        exit(1);
    }
     printf("[+]Server socket created. \n");
     server_addr.sin_family = AF_INET;
     server_addr.sin_port = port;
     server_addr.sin_addr.s_addr = inet_addr(ip);
     e = connect(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));
     if(e == -1){
         perror("[-]Error in Connecting");
         exit(1);
     }
     printf("[+]Connected to server.\n");
     fp = fopen(filename, "r");
     if(fp == NULL){
         perror("[-]Error in reading file.");
         exit(1);
     }
     send_file(fp,sockfd);
     printf("[+] File data send successfully. \n");
     close(sockfd);
     printf("[+]Disconnected from the server. \n");
     return 0;
}

Output files:

This is the Terminal:

I try this code on a Windows machine.

Please help me to fix this problem.