Programming Forums > Application Development > C++

Ghosty · Dec 14th, 2006, 7:05 PM

The following code will print prime numbers and output them to a file specified by the user. Also, it will call the alarm() based on values passed on the command line. The SIGALRM and the SIGUSR1 will cause the program to print the last prime number generated. I'm having problems doing my write(). It should be the most straightforward function but I'm really tired and I can't seem to figure it out. There's also a bug with the way I implemented my command line arguments to call the alarm() but I'm not requesting help with that. I just haven't gotten to fixing it yet.

Thanks in advance. Sorry for how ugly the code is.

(Toggle Plain Text)

#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <list>
#include <algorithm>
#include <fcntl.h>

using namespace std;

void generatePrimesFile(int*, char*);
void usr1_handler(int);
void alarm_handler(int);
list<int> alarm_values;

//I don't like globals but we can't pass the handler functions anything
int currentPrime = 1;

int main(int argc, char *argv[]) {
	if(argc < 2){
		cerr << "Usage: Lab6 <file to be written> <optional time>" << endl;
		return 1;
	}
	char * name = argv[1];
	int * cp_ptr = &currentPrime;

    // Setup the signal handlers
    struct sigaction usr1Act;
	struct sigaction alarmAct;
    usr1Act.sa_handler = usr1_handler;
	sigemptyset( &usr1Act.sa_mask );
	usr1Act.sa_flags = SA_RESTART;
	
	alarmAct.sa_handler = alarm_handler;
	sigemptyset( &alarmAct.sa_mask);
	alarmAct.sa_flags = SA_RESTART;
	
    if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) {
		//syserr("sigaction");
    	perror( "sigaction" );
    	exit( 1 );
	}

	if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) {
		perror( "sigaction alarm");
		exit(1); 
	}
	//fill alarm values list
	alarm_values.clear();
	for(int i= 2; i < argc; i++){
		alarm_values.push_back(i);
	}
	//sort it
	alarm_values.unique();
	alarm_values.sort();
	//set the alarm to the lowest value in the list
	alarm( alarm_values.front() );
	
	generatePrimesFile(cp_ptr, name);
}

void usr1_handler(int signo){
	cout << "Current Prime: " << currentPrime << endl;
}

void alarm_handler(int signo) {
	cout << "Current Prime: " << currentPrime << endl;
	if(!alarm_values.empty()){
		int temp = alarm_values.front();
		alarm_values.pop_front();
		alarm( alarm_values.front() - temp );
	}
}
 
void generatePrimesFile(int * currentPrime, char* name) {
		const int BIGNUMBER = 65534;
		bool isPrime=true;
		
		int fd;
		if( (fd = open(name, O_WRONLY|O_APPEND|O_CREAT, 0700)) == -1){
			perror("open");
			exit(1);
		}

		for ( int i = 0; i < BIGNUMBER; i++) {
				for ( int j = 2; j < BIGNUMBER; j++) {
						if ( i!=j && i % j == 0 ) {
						  isPrime=false;
						  break;
						}
				}
				if (isPrime) {
					*currentPrime = i;
					int buff[] = {i};
					write(fd, buff, 2);
					sleep(1);
				}
				isPrime=true;
		}
}

#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <list>
#include <algorithm>
#include <fcntl.h>

using namespace std;

void generatePrimesFile(int*, char*);
void usr1_handler(int);
void alarm_handler(int);
list<int> alarm_values;

//I don't like globals but we can't pass the handler functions anything
int currentPrime = 1;

int main(int argc, char *argv[]) {
	if(argc < 2){
		cerr << "Usage: Lab6 <file to be written> <optional time>" << endl;
		return 1;
	}
	char * name = argv[1];
	int * cp_ptr = &currentPrime;

    // Setup the signal handlers
    struct sigaction usr1Act;
	struct sigaction alarmAct;
    usr1Act.sa_handler = usr1_handler;
	sigemptyset( &usr1Act.sa_mask );
	usr1Act.sa_flags = SA_RESTART;
	
	alarmAct.sa_handler = alarm_handler;
	sigemptyset( &alarmAct.sa_mask);
	alarmAct.sa_flags = SA_RESTART;
	
    if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) {
		//syserr("sigaction");
    	perror( "sigaction" );
    	exit( 1 );
	}

	if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) {
		perror( "sigaction alarm");
		exit(1); 
	}
	//fill alarm values list
	alarm_values.clear();
	for(int i= 2; i < argc; i++){
		alarm_values.push_back(i);
	}
	//sort it
	alarm_values.unique();
	alarm_values.sort();
	//set the alarm to the lowest value in the list
	alarm( alarm_values.front() );
	
	generatePrimesFile(cp_ptr, name);
}

void usr1_handler(int signo){
	cout << "Current Prime: " << currentPrime << endl;
}

void alarm_handler(int signo) {
	cout << "Current Prime: " << currentPrime << endl;
	if(!alarm_values.empty()){
		int temp = alarm_values.front();
		alarm_values.pop_front();
		alarm( alarm_values.front() - temp );
	}
}
 
void generatePrimesFile(int * currentPrime, char* name) {
		const int BIGNUMBER = 65534;
		bool isPrime=true;
		
		int fd;
		if( (fd = open(name, O_WRONLY|O_APPEND|O_CREAT, 0700)) == -1){
			perror("open");
			exit(1);
		}

		for ( int i = 0; i < BIGNUMBER; i++) {
				for ( int j = 2; j < BIGNUMBER; j++) {
						if ( i!=j && i % j == 0 ) {
						  isPrime=false;
						  break;
						}
				}
				if (isPrime) {
					*currentPrime = i;
					int buff[] = {i};
					write(fd, buff, 2);
					sleep(1);
				}
				isPrime=true;
		}
}

Game_Ender · Dec 14th, 2006, 7:15 PM

Did you even look up the prototype of write?

(Toggle Plain Text)

ssize_t write(int fildes, const void *buf, size_t nbyte);

You need a char buffer, not an int one. After you have done that use itoa to turn the number into a character. Then just call write with that buffer.

Ghosty · Dec 14th, 2006, 8:43 PM

Well that certainly explains why I wasn't getting readable files. But I included <stdlib.h> and itoa() is reported as undefined. Does Gcc not support it?

Edit: A little googling made me aware of sprintf(). I'm going to try that.
Edit2: sprintf works for my purposes.

Ghosty · Dec 14th, 2006, 11:16 PM

This code works for the most part. I don't know how to format the output though. Ideally, I'd like the output file to look similar to this:

(Toggle Plain Text)

1
2
3
5
7
11
13
and so on with primes

Thanks in advance and again sorry for the mess.

(Toggle Plain Text)

#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <list>
#include <algorithm>
#include <fcntl.h>
#include <cstdio>
#include <signal.h>

using namespace std;

void generatePrimesFile(int*, char*);
void usr1_handler(int);
void alarm_handler(int); 

//I don't like globals but we can't pass the handler functions anything
int currentPrime = 1;
list<int> alarm_values;

int main(int argc, char *argv[]) {
	if(argc < 2){
		cerr << "Usage: Lab6 <file to be written> <optional time>" << endl;
		return 1;
	}
	char * name = argv[1];
	int * cp_ptr = &currentPrime;

    // Setup the signal handlers
    struct sigaction usr1Act;
	struct sigaction alarmAct;
    usr1Act.sa_handler = usr1_handler;
	sigemptyset( &usr1Act.sa_mask );
	usr1Act.sa_flags = SA_RESTART;
	
	alarmAct.sa_handler = alarm_handler;
	sigemptyset( &alarmAct.sa_mask);
	alarmAct.sa_flags = SA_RESTART;
	
    if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) {
		//syserr("sigaction");
    	perror( "sigaction" );
    	exit( 1 );
	}

	if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) {
		perror( "sigaction alarm");
		exit(1); 
	}
	//fill alarm values list
	alarm_values.clear();
	for(int i= 2; i < argc; i++){
		alarm_values.push_back(atoi(argv[i]));
	}
	//sort it
	alarm_values.unique();
	alarm_values.sort();
	//set the alarm to the lowest value in the list
	alarm( alarm_values.front() );
	
	generatePrimesFile(cp_ptr, name);
}

void usr1_handler(int signo){
	cout << "Current Prime: " << currentPrime << endl;
}

void alarm_handler(int signo) {
	cout << "Current Prime: " << currentPrime << endl;
	if(!alarm_values.empty()){
		int temp = alarm_values.front();
		alarm_values.pop_front();
		alarm( alarm_values.front() - temp );
	}
}
 
void generatePrimesFile(int * currentPrime, char* name) {
		const int BIGNUMBER = 2000;
		bool isPrime=true;
		
		int fd;
		if( (fd = open(name, O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, 0700)) == -1){
			perror("open");
			exit(1);
		}

		for ( int i = 0; i < BIGNUMBER; i++) {
				for ( int j = 2; j < BIGNUMBER; j++) {
						if ( i!=j && i % j == 0 ) {
						  isPrime=false;
						  break;
						}
				}
				if (isPrime) {
					*currentPrime = i;
					char buff[500];
					int n = sprintf( buff, "%d", i );
					buff[n+1] += '\0';              
					write(fd, buff, n+1);
					sleep(1);
				}
				isPrime=true;
		}
}

#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <list>
#include <algorithm>
#include <fcntl.h>
#include <cstdio>
#include <signal.h>

using namespace std;

void generatePrimesFile(int*, char*);
void usr1_handler(int);
void alarm_handler(int); 

//I don't like globals but we can't pass the handler functions anything
int currentPrime = 1;
list<int> alarm_values;

int main(int argc, char *argv[]) {
	if(argc < 2){
		cerr << "Usage: Lab6 <file to be written> <optional time>" << endl;
		return 1;
	}
	char * name = argv[1];
	int * cp_ptr = &currentPrime;

    // Setup the signal handlers
    struct sigaction usr1Act;
	struct sigaction alarmAct;
    usr1Act.sa_handler = usr1_handler;
	sigemptyset( &usr1Act.sa_mask );
	usr1Act.sa_flags = SA_RESTART;
	
	alarmAct.sa_handler = alarm_handler;
	sigemptyset( &alarmAct.sa_mask);
	alarmAct.sa_flags = SA_RESTART;
	
    if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) {
		//syserr("sigaction");
    	perror( "sigaction" );
    	exit( 1 );
	}

	if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) {
		perror( "sigaction alarm");
		exit(1); 
	}
	//fill alarm values list
	alarm_values.clear();
	for(int i= 2; i < argc; i++){
		alarm_values.push_back(atoi(argv[i]));
	}
	//sort it
	alarm_values.unique();
	alarm_values.sort();
	//set the alarm to the lowest value in the list
	alarm( alarm_values.front() );
	
	generatePrimesFile(cp_ptr, name);
}

void usr1_handler(int signo){
	cout << "Current Prime: " << currentPrime << endl;
}

void alarm_handler(int signo) {
	cout << "Current Prime: " << currentPrime << endl;
	if(!alarm_values.empty()){
		int temp = alarm_values.front();
		alarm_values.pop_front();
		alarm( alarm_values.front() - temp );
	}
}
 
void generatePrimesFile(int * currentPrime, char* name) {
		const int BIGNUMBER = 2000;
		bool isPrime=true;
		
		int fd;
		if( (fd = open(name, O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, 0700)) == -1){
			perror("open");
			exit(1);
		}

		for ( int i = 0; i < BIGNUMBER; i++) {
				for ( int j = 2; j < BIGNUMBER; j++) {
						if ( i!=j && i % j == 0 ) {
						  isPrime=false;
						  break;
						}
				}
				if (isPrime) {
					*currentPrime = i;
					char buff[500];
					int n = sprintf( buff, "%d", i );
					buff[n+1] += '\0';              
					write(fd, buff, n+1);
					sleep(1);
				}
				isPrime=true;
		}
}

DaWei · Dec 15th, 2006, 6:11 AM

You need to be more than aware of sprintf; you need to read its docs (and possibly follow the link to printf). If you want a newline after the number, consider using "%d\n".

Ghosty · Dec 15th, 2006, 1:59 PM

You are indeed right DaWei. I was in a rush to fix the code and didn't bother reading up on sprintf. I have the code working however.

Thanks for the help GE.

lectricpharaoh · Dec 15th, 2006, 9:48 PM

Quote:

Originally Posted by Ghosty

Well that certainly explains why I wasn't getting readable files. But I included <stdlib.h> and itoa() is reported as undefined. Does Gcc not support it?

There is no itoa() in standard C (or C++). It's a compiler-specific function present in some compilers.

Quote:

Originally Posted by Ghosty

Edit: A little googling made me aware of sprintf(). I'm going to try that.

Yes, that would be my suggestion. As DaWei mentioned, you need to be 'more than aware' of it. There is also a risk of buffer overflows; however, since the source is a value with a defined and known range, it's relatively trivial to ensure that the destination string is allocated with sufficient size. The various minimums and maximums for integer values are stored in <limits.h>; you can use these values at run time to allocate a defined buffer size, or (preferably) at compile time via conditional compilation to set a symbolic constant to the appropriate size. Don't forget the terminating zero.

An alternative that avoids all of these allocation size issues would be to use stringstreams. This lets you use the stream I/O syntax you're already familiar with. Info to get you started can be found here.

Ghosty · Dec 17th, 2006, 11:21 PM

Quote:

Originally Posted by lectricpharaoh

An alternative that avoids all of these allocation size issues would be to use stringstreams. This lets you use the stream I/O syntax you're already familiar with. Info to get you started can be found here.

Thanks for the link. I'm definitely going to read up on string streams.

Dec 14th, 2006, 7:05 PM	#1
Ghosty Newbie Join Date: May 2005 Location: NJ Posts: 18 Rep Power: 0	new unix problem: signals and write() calls The following code will print prime numbers and output them to a file specified by the user. Also, it will call the alarm() based on values passed on the command line. The SIGALRM and the SIGUSR1 will cause the program to print the last prime number generated. I'm having problems doing my write(). It should be the most straightforward function but I'm really tired and I can't seem to figure it out. There's also a bug with the way I implemented my command line arguments to call the alarm() but I'm not requesting help with that. I just haven't gotten to fixing it yet. Thanks in advance. Sorry for how ugly the code is. (Toggle Plain Text) #include <iostream> #include <unistd.h> #include <sys/wait.h> #include <list> #include <algorithm> #include <fcntl.h> using namespace std; void generatePrimesFile(int, char); void usr1_handler(int); void alarm_handler(int); list<int> alarm_values; //I don't like globals but we can't pass the handler functions anything int currentPrime = 1; int main(int argc, char argv[]) { if(argc < 2){ cerr << "Usage: Lab6 <file to be written> <optional time>" << endl; return 1; } char name = argv[1]; int * cp_ptr = &currentPrime; // Setup the signal handlers struct sigaction usr1Act; struct sigaction alarmAct; usr1Act.sa_handler = usr1_handler; sigemptyset( &usr1Act.sa_mask ); usr1Act.sa_flags = SA_RESTART; alarmAct.sa_handler = alarm_handler; sigemptyset( &alarmAct.sa_mask); alarmAct.sa_flags = SA_RESTART; if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) { //syserr("sigaction"); perror( "sigaction" ); exit( 1 ); } if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) { perror( "sigaction alarm"); exit(1); } //fill alarm values list alarm_values.clear(); for(int i= 2; i < argc; i++){ alarm_values.push_back(i); } //sort it alarm_values.unique(); alarm_values.sort(); //set the alarm to the lowest value in the list alarm( alarm_values.front() ); generatePrimesFile(cp_ptr, name); } void usr1_handler(int signo){ cout << "Current Prime: " << currentPrime << endl; } void alarm_handler(int signo) { cout << "Current Prime: " << currentPrime << endl; if(!alarm_values.empty()){ int temp = alarm_values.front(); alarm_values.pop_front(); alarm( alarm_values.front() - temp ); } } void generatePrimesFile(int * currentPrime, char* name) { const int BIGNUMBER = 65534; bool isPrime=true; int fd; if( (fd = open(name, O_WRONLY\|O_APPEND\|O_CREAT, 0700)) == -1){ perror("open"); exit(1); } for ( int i = 0; i < BIGNUMBER; i++) { for ( int j = 2; j < BIGNUMBER; j++) { if ( i!=j && i % j == 0 ) { isPrime=false; break; } } if (isPrime) { currentPrime = i; int buff[] = {i}; write(fd, buff, 2); sleep(1); } isPrime=true; } } #include <iostream> #include <unistd.h> #include <sys/wait.h> #include <list> #include <algorithm> #include <fcntl.h> using namespace std; void generatePrimesFile(int, char); void usr1_handler(int); void alarm_handler(int); list<int> alarm_values; //I don't like globals but we can't pass the handler functions anything int currentPrime = 1; int main(int argc, char argv[]) { if(argc < 2){ cerr << "Usage: Lab6 <file to be written> <optional time>" << endl; return 1; } char * name = argv[1]; int * cp_ptr = &currentPrime; // Setup the signal handlers struct sigaction usr1Act; struct sigaction alarmAct; usr1Act.sa_handler = usr1_handler; sigemptyset( &usr1Act.sa_mask ); usr1Act.sa_flags = SA_RESTART; alarmAct.sa_handler = alarm_handler; sigemptyset( &alarmAct.sa_mask); alarmAct.sa_flags = SA_RESTART; if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) { //syserr("sigaction"); perror( "sigaction" ); exit( 1 ); } if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) { perror( "sigaction alarm"); exit(1); } //fill alarm values list alarm_values.clear(); for(int i= 2; i < argc; i++){ alarm_values.push_back(i); } //sort it alarm_values.unique(); alarm_values.sort(); //set the alarm to the lowest value in the list alarm( alarm_values.front() ); generatePrimesFile(cp_ptr, name); } void usr1_handler(int signo){ cout << "Current Prime: " << currentPrime << endl; } void alarm_handler(int signo) { cout << "Current Prime: " << currentPrime << endl; if(!alarm_values.empty()){ int temp = alarm_values.front(); alarm_values.pop_front(); alarm( alarm_values.front() - temp ); } } void generatePrimesFile(int * currentPrime, char* name) { const int BIGNUMBER = 65534; bool isPrime=true; int fd; if( (fd = open(name, O_WRONLY\|O_APPEND\|O_CREAT, 0700)) == -1){ perror("open"); exit(1); } for ( int i = 0; i < BIGNUMBER; i++) { for ( int j = 2; j < BIGNUMBER; j++) { if ( i!=j && i % j == 0 ) { isPrime=false; break; } } if (isPrime) { *currentPrime = i; int buff[] = {i}; write(fd, buff, 2); sleep(1); } isPrime=true; } }

Dec 14th, 2006, 7:15 PM	#2
Game_Ender Professional Programmer Join Date: May 2006 Location: Maryland, USA Posts: 306 Rep Power: 3	Did you even look up the prototype of write? (Toggle Plain Text) ssize_t write(int fildes, const void buf, size_t nbyte); ssize_t write(int fildes, const void buf, size_t nbyte); You need a char buffer, not an int one. After you have done that use itoa to turn the number into a character. Then just call write with that buffer.

Dec 14th, 2006, 8:43 PM	#3
Ghosty Newbie Join Date: May 2005 Location: NJ Posts: 18 Rep Power: 0	Well that certainly explains why I wasn't getting readable files. But I included <stdlib.h> and itoa() is reported as undefined. Does Gcc not support it? Edit: A little googling made me aware of sprintf(). I'm going to try that. Edit2: sprintf works for my purposes. Last edited by Ghosty; Dec 14th, 2006 at 9:27 PM.

Dec 14th, 2006, 11:16 PM	#4
Ghosty Newbie Join Date: May 2005 Location: NJ Posts: 18 Rep Power: 0	This code works for the most part. I don't know how to format the output though. Ideally, I'd like the output file to look similar to this: (Toggle Plain Text) 1 2 3 5 7 11 13 and so on with primes 1 2 3 5 7 11 13 and so on with primes Thanks in advance and again sorry for the mess. (Toggle Plain Text) #include <iostream> #include <unistd.h> #include <sys/wait.h> #include <list> #include <algorithm> #include <fcntl.h> #include <cstdio> #include <signal.h> using namespace std; void generatePrimesFile(int, char); void usr1_handler(int); void alarm_handler(int); //I don't like globals but we can't pass the handler functions anything int currentPrime = 1; list<int> alarm_values; int main(int argc, char argv[]) { if(argc < 2){ cerr << "Usage: Lab6 <file to be written> <optional time>" << endl; return 1; } char name = argv[1]; int * cp_ptr = &currentPrime; // Setup the signal handlers struct sigaction usr1Act; struct sigaction alarmAct; usr1Act.sa_handler = usr1_handler; sigemptyset( &usr1Act.sa_mask ); usr1Act.sa_flags = SA_RESTART; alarmAct.sa_handler = alarm_handler; sigemptyset( &alarmAct.sa_mask); alarmAct.sa_flags = SA_RESTART; if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) { //syserr("sigaction"); perror( "sigaction" ); exit( 1 ); } if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) { perror( "sigaction alarm"); exit(1); } //fill alarm values list alarm_values.clear(); for(int i= 2; i < argc; i++){ alarm_values.push_back(atoi(argv[i])); } //sort it alarm_values.unique(); alarm_values.sort(); //set the alarm to the lowest value in the list alarm( alarm_values.front() ); generatePrimesFile(cp_ptr, name); } void usr1_handler(int signo){ cout << "Current Prime: " << currentPrime << endl; } void alarm_handler(int signo) { cout << "Current Prime: " << currentPrime << endl; if(!alarm_values.empty()){ int temp = alarm_values.front(); alarm_values.pop_front(); alarm( alarm_values.front() - temp ); } } void generatePrimesFile(int * currentPrime, char* name) { const int BIGNUMBER = 2000; bool isPrime=true; int fd; if( (fd = open(name, O_WRONLY\|O_APPEND\|O_CREAT\|O_TRUNC, 0700)) == -1){ perror("open"); exit(1); } for ( int i = 0; i < BIGNUMBER; i++) { for ( int j = 2; j < BIGNUMBER; j++) { if ( i!=j && i % j == 0 ) { isPrime=false; break; } } if (isPrime) { currentPrime = i; char buff[500]; int n = sprintf( buff, "%d", i ); buff[n+1] += '\0'; write(fd, buff, n+1); sleep(1); } isPrime=true; } } #include <iostream> #include <unistd.h> #include <sys/wait.h> #include <list> #include <algorithm> #include <fcntl.h> #include <cstdio> #include <signal.h> using namespace std; void generatePrimesFile(int, char); void usr1_handler(int); void alarm_handler(int); //I don't like globals but we can't pass the handler functions anything int currentPrime = 1; list<int> alarm_values; int main(int argc, char argv[]) { if(argc < 2){ cerr << "Usage: Lab6 <file to be written> <optional time>" << endl; return 1; } char * name = argv[1]; int * cp_ptr = &currentPrime; // Setup the signal handlers struct sigaction usr1Act; struct sigaction alarmAct; usr1Act.sa_handler = usr1_handler; sigemptyset( &usr1Act.sa_mask ); usr1Act.sa_flags = SA_RESTART; alarmAct.sa_handler = alarm_handler; sigemptyset( &alarmAct.sa_mask); alarmAct.sa_flags = SA_RESTART; if( sigaction( SIGUSR1 , &usr1Act, NULL ) == -1 ) { //syserr("sigaction"); perror( "sigaction" ); exit( 1 ); } if( sigaction( SIGALRM, &alarmAct, NULL) == -1 ) { perror( "sigaction alarm"); exit(1); } //fill alarm values list alarm_values.clear(); for(int i= 2; i < argc; i++){ alarm_values.push_back(atoi(argv[i])); } //sort it alarm_values.unique(); alarm_values.sort(); //set the alarm to the lowest value in the list alarm( alarm_values.front() ); generatePrimesFile(cp_ptr, name); } void usr1_handler(int signo){ cout << "Current Prime: " << currentPrime << endl; } void alarm_handler(int signo) { cout << "Current Prime: " << currentPrime << endl; if(!alarm_values.empty()){ int temp = alarm_values.front(); alarm_values.pop_front(); alarm( alarm_values.front() - temp ); } } void generatePrimesFile(int * currentPrime, char* name) { const int BIGNUMBER = 2000; bool isPrime=true; int fd; if( (fd = open(name, O_WRONLY\|O_APPEND\|O_CREAT\|O_TRUNC, 0700)) == -1){ perror("open"); exit(1); } for ( int i = 0; i < BIGNUMBER; i++) { for ( int j = 2; j < BIGNUMBER; j++) { if ( i!=j && i % j == 0 ) { isPrime=false; break; } } if (isPrime) { *currentPrime = i; char buff[500]; int n = sprintf( buff, "%d", i ); buff[n+1] += '\0'; write(fd, buff, n+1); sleep(1); } isPrime=true; } }

Dec 15th, 2006, 6:11 AM	#5
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	You need to be more than aware of sprintf; you need to read its docs (and possibly follow the link to printf). If you want a newline after the number, consider using "%d\n". __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Dec 15th, 2006, 1:59 PM	#6
Ghosty Newbie Join Date: May 2005 Location: NJ Posts: 18 Rep Power: 0	You are indeed right DaWei. I was in a rush to fix the code and didn't bother reading up on sprintf. I have the code working however. Thanks for the help GE.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Programming Forums > Application Development > C++

new unix problem: signals and write() calls