(ALT 2) QUIZ II Operating System (SERVER)

// LINK SOAL : https://www.dropbox.com/sh/wussgfrqrmazf9g/AADnp_e-zKkHZWXyAFDQ5yJFa?dl=0
// LINK TEMPLATE : http://pastebin.com/Rc7A08xG

#include <stdio.h>
#include <sys/ipc.h>
#include <sys/types.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <ctype.h>

struct data{
    char nama[25];
    char cc[17];
    float sale;
};

int main(){
    struct sembuf s;
    int h=shmget(123456,sizeof(struct data),IPC_CREAT|0666);
    int e=semget(123456,1,IPC_CREAT|0666);
    semctl(e,0,SETVAL,0);
    struct data *card=(struct data *)shmat(h,NULL,0666);
    printf("/=================================\\\n");
    printf("|Blue Jack Card Processing System |\n");
    printf("\\=================================/\n\n");
    printf("Server\n------\n\n");
    do{
        int i=0;
        s.sem_num=0;
        s.sem_op=-1;
        s.sem_flg=0;
        semop(e,&s,1);
        if(strcasecmp(card->nama,"exit")!=0){
            printf("Card Transaction\nBluejack Card Network\n---------------------------------\n");
            printf("Masked CC : ");
            for(i=0;i<strlen(card->cc);i++){
                if(i<6)
                    printf("%c",card->cc[i]);
                else if(i<12)
                    printf("*");
                else
                    printf("%c",card->cc[i]);
            }
            printf("\n");
            printf("Card Holder  \t: %s\n",card->nama);
            int r1,r2;
            srand(time(NULL));
            r1=rand()%26+(int)'A';
            r2=rand()%26+(int)'A';
            printf("Approval Code\t: %c%c%c%c%c%c\n",r1,r2,card->cc[12],card->cc[13],card->cc[14],card->cc[15]);
            printf("Sale Amount  \t: $ %10.2f\n",card->sale);
            float pf;
            pf=0.03*card->sale+0.1;
            printf("Processing Fee \t: $ %10.2f\n",pf);
            printf("--------------------------------+\n");
            printf("Total Payment  \t: $ %10.2f\n\n",pf+card->sale);
        }

    }while(strcasecmp(card->nama,"exit")!=0);
    shmdt(&s);
    shmctl(h,IPC_RMID,0);
    semctl(e,0,IPC_RMID);
    return 0;
}