CODEWITHSUNDEEP
cunixstdin
Leo103
Leo103

Reputation: 871

How to read numbers from stdin until end

Where there is for(;;) I need something to read from stdin and save to N. Something with read(stdin,N,sizeof(float)) and while(s!=EOF) s=getc(stdin) maybe? I'm assuming a list of numbers is saved on stdin separated end of lines

The question was something like:

Your program must print its pid to standard output. Then it should start to read values of N from standard input until the end of the file. After receiving a signal (SIGUSR1) your program should subtract (then multiply, then divide, then subtract) the value of N from sum (first value of sum=0) as a cycle. After receiving SIGUSR2 your program should print the current sum.

How I interpreted the question and attempt:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>

float N,sum=0;
int count=0;

void handler(int s){
    count++;
    if (s==SIGUSR1){
        if (count==1){
            sum-=N;
        }   
        if (count==2){
            sum*=N;
        }
        if (count==3){
            sum/=N;
        }
        if (count==4){
            sum+=N;
            count==0;
        }

    }

    else if (s==SIGUSR2){
        printf("sum=%d",sum);
    }
}


int main(){
    pid_t pid=getpid();
    signal(SIGUSR1,handler);
    signal(SIGUSR2,handler);
    printf("%d",pid);
    fflush(stdout); 

    for(;;)
    scanf("%d",&N);


    return(0);
}

Upvotes: 0

Views: 1946

Answers (1)

John Kugelman
John Kugelman

Reputation: 361635

Check the return value of scanf. It returns the number of items successfully matched, so if it doesn't return 1 then you're done.

while (scanf("%d", &N) == 1)
    ;

Upvotes: 1

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