How can I stop the while?

I have A TCP Server-Client where I enter a number with the number of times that I want to send the word to the server. So I send correctly because I print the information on a loop(in client) but in the server shows infinitely because I put while(1) but if I don’t use just print it one time. I don’t want to send the number to the server.

If I enter the number 4 I want to print the word “hello” four times This is the server, now it’s printing infinitely obviously.

#define MAXPENDING 5    /* Maximum number of simultaneous connections */
#define BUFFSIZE 255    /* Size of message to be received */

void err_sys(char *mess) { perror(mess); exit(1); }

void handle_client(int sock) {
    char buffer[BUFFSIZE];
    int received = -1;
    while (1) {
        /* Read from socket */
        read(sock, &buffer[0], BUFFSIZE);
        printf("Message from client: %sn", buffer);

        /* Write to socket */
        write(sock, buffer, strlen(buffer) + 1);

        /* Close socket */
        close(sock);
    }
}
int main(int argc, char *argv[]) {
    struct sockaddr_in echoserver, echoclient;
    int serversock, clientsock;
    int result;

    /* Check input arguments */
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <port>n", argv[0]);
        exit(1);
    }

    /* Create TCP socket */
    serversock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serversock < 0) {
        err_sys("Error socket");
    }

    /* Set information for sockaddr_in structure */
    memset(&echoserver, 0, sizeof(echoserver));       /* we reset memory */
    echoserver.sin_family = AF_INET;                  /* Internet/IP */
    echoserver.sin_addr.s_addr = htonl(INADDR_ANY);   /* ANY address */
    echoserver.sin_port = htons(atoi(argv[1]));       /* server port */

    /* Bind socket */
    result = bind(serversock, (struct sockaddr *) &echoserver, sizeof(echoserver));
    if (result < 0) {
        err_sys("Error bind");
    }

    /* Listen socket */
    result = listen(serversock, MAXPENDING);
    if (result < 0) {
        err_sys("Error listen");
    }
    while (1) {
        unsigned int clientlen = sizeof(echoclient);

        /* Wait for a connection from a client */
        clientsock = accept(serversock, (struct sockaddr *) &echoclient, &clientlen);
        if (clientsock < 0) {
            err_sys("Error accept");
        }
        fprintf(stdout, "Client: %sn", inet_ntoa(echoclient.sin_addr));

        /* Call function to handle socket */
        handle_client(clientsock);
    }
}

This is the client

  printf("Enter a number between 0 to 9[0 to exit]: ");
fgets(number, 100, stdin);
while(strtol(number,&pEnd,10)!=0){

    while (!((strtol(number,&pEnd,10) <= 9) && (strtol(number,&pEnd,10) >= 0))) {
        printf("[ERROR] The number you entered is out of rangen");
        printf("Enter a number between 0 to 9[0 to exit]: ");
        fgets(number, 100, stdin);
    }
    if(strtol(number,&pEnd,10)!=0){
        printf("Enter a word: ");
        fgets(buffer, 100, stdin);
        for(int i=0;i<strtol(number,&pEnd,10);i++){
            write(sock, buffer, strlen(buffer) + 1);
            fprintf(stdout, " sent n");

            read(sock, buffer, BUFFSIZE);
            fprintf(stdout, " %s ...done n", buffer);
        }

    }
    printf(" Enter a number between 0 to 9[0 to exit]: ");
    fgets(number, 100, stdin);
}

Answer

There are multiple problems in you code:

• you do not test if read() succeeds. You should break from the loop if it fails.
• you unconditionally close the socket in the body of the loop: the next read will fail and return -1 immediately, you will print a bogus message and iterate at nauseam.
• you call strlen() and printf() with a buffer that might not be null terminated, potentially causing undefined behavior.

Here is a modified version:

void handle_client(int sock) {
    char buffer[BUFFSIZE];
    int received = -1;
    if (sock < 0)
        return;
    for (;;) {
        /* Read from socket */
        received = read(sock, buffer, sizeof(buffer) - 1);
        if (received <= 0)
            break;
        buffer[received] = '';
        printf("Message from client: %sn", buffer);

        /* Write to socket */
        write(sock, buffer, received);
    }
    /* Close socket */
    close(sock);
}