C Programmers Help Me!!!!

chamidilk · Feb 14, 2009

Lab6-E.1-menna prime numbers

1st solution(dz 1 z mine)-dz prog z de fastest 1 in investigating a prime

Code:

#include<stdio.h>
main(){
	int i,s,ip;
	scanf("%d",&s);
	while(s!=-1){
		if(s==2)printf("prime\n");
		else if(s%2==0);
		else {
			if(s!=1){
				ip=1;
				for(i=2;i*i<=s;i++){
					if(s%i==0){
						ip=-1;
						break;
					}
				}
				if(ip==1)printf("prime\n");
			}
		}
		scanf("%d",&s);
	}
}

2nd solution which u all like very much

Code:

#include<stdio.h>
main(){
	int s,i,j,ip;
	scanf("%d",&s);
	while(s!=-1){
		if(s==2||s==3)printf("prime\n");
		else{
			if(s!=1){
				ip=1;
				for(j=3;j<s;j+=1){
					if(s%j==0){
						ip=-1;break;
					}
				}
				if(ip==1)printf("prime\n");
			}
		}
		scanf("%d",&s);
	}
}

madurax86 · Feb 14, 2009

C++ version, C paranai ne meka kochara simpla plan ekak da?

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    bool isprime;
    cin>>n;
    isprime=true;
    i=abs(n); //neglect negative numbers
    n=i;
    while (i>2) {
          i--;
          if (n%i==0) {isprime=false; break;} ;
          }         
    if (isprime==1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

madurax86 · Feb 14, 2009

double post, due to server load srry

chamidilk · Feb 14, 2009

menna ithiri progs2E.2 & E.3

Exercise 2-

Code:

#include<stdio.h>
main(){
	int i,j,k;
	scanf("%d",&k);
	while(k!=-1){
		for(i=1;i<k;i++){
			if(k%i==0)j+=i;
		}
		if(j==k)printf("perfect\n");
		j=0;
		scanf("%d",&k);
	}
}

Exercise 3-

Code:

#include<stdio.h>
main(){
	int i,j;
	for(j=0;j<5;j++){
		for(i=6;i>j;i--)printf("$");
		printf("\n");
	}
	printf("$\n");
	for(j=0;j<5;j++){
		for(i=0;i<j+2;i++)printf("$");
		printf("\n");
	}
}

chamidilk · Feb 14, 2009

please

madurax86 said:

C++ version, C paranai ne meka kochara simpla plan ekak da?

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    bool isprime;
    cin>>n;
    isprime=true;
    i=abs(n); //neglect negative numbers
    n=i;
    while (i>2) {
          i--;
          if (n%i==0) {isprime=false; break;} ;
          }         
    if (isprime==1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

i appreciate your postings here
please bro
cn u please correct ur code and put t back here
my uni mates will be confused in ur prog

madurax86 · Feb 14, 2009

chamidilk said:
i appreciate your postings here
please bro
cn u please correct ur code and put t back here
my uni mates will be confused in ur prog

correct what? it works fine with mingw32 compiler its C++ not C

chamidilk · Feb 14, 2009

please

madurax86 said:
correct what? it works fine with mingw32 compiler its C++ not C

r u sure check t back n tell me

madurax86 · Feb 14, 2009

chamidilk said:
r u sure check t back n tell me

sure dath kiyala ahanawa

chamidilk · Feb 14, 2009

check

check whether 2 is a prime or not using your prog .......
I am sure your prog hz a mistake

madurax86 · Feb 14, 2009

chamidilk said:
check whether 2 is a prime or not using your prog .......
I am sure your prog hz a mistake

I didnt change anything it works well man

i edited the code some while ago(before you said it has a bug) to make it shorter after posting in EK u may have copied the program then copy it now and see

I copied the code from EK then compiled a new project same result(this is the exact code that u quoted)

Just by looking at the code you can say that 2 is never being passed thru the algorithm only numbers greater than 2, i=2 is bypassed and returns prime, its the same for 1 too

chamidilk · Feb 14, 2009

hmmmmm
fine ur prog z correct ....

sorry .......i dint get tht de value n .... actually by mistake t wz commented
thts y t did an error

bt still thr z n error

t gives u 1 is a prime ...
z t correct my dear ???????
1 is nt a prime although ts facors r 1 n tself only

n next error z u r investigating whether even numbers r primes xcluding 2 .......

bt u r doing a very gud contribution 2 my C knowledge n my mates ....
keep posting

chamidilk · Feb 14, 2009

menna oyage CPP prog eka modify kala - poddak speedup wei

madurax86 said:

C++ version, C paranai ne meka kochara simpla plan ekak da?

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    int isprime;
    cin>>n;
    isprime=true;
    i=abs(n); //neglect negative numbers
    n=i;
    while (i>2) {
          if(n%2==0){isprime=-1;break;}
          i--;
          if (n%i==0) {isprime=false; break;} ;
          }         
    if (isprime==1&&n!=1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

meke 1 prime ekak widiyata ganne naha
anika even numbers >2 wil nt b processed

madurax86 · Feb 14, 2009

chamidilk said:
hmmmmm
fine ur prog z correct ....

sorry .......i dint get tht de value n .... actually by mistake t wz commented
thts y t did an error

bt still thr z n error

t gives u 1 is a prime ...
z t correct my dear ???????
1 is nt a prime although ts facors r 1 n tself only

n next error z u r investigating whether even numbers r primes xcluding 2 .......

bt u r doing a very gud contribution 2 my C knowledge n my mates ....
keep posting

i did think that 1 is a prime when i was coding

it should be it is dividable by 1 and itself which we see as a common thing in all other prime numbers, its just a definition not actual math. I didnt now the definition at the time of coding and i thought of the common factor in all primes and included 1 as a prime too
The program is only made for integers not real numbers so excluding 2 and even 3 would not result in a wrong output because isprime is assigned true at the beginning and if some number was lesser than 2 then it would do nothing, the while would not execute and the answer will be delivered through a shortcut you can put i>3 also it wont result in wrong outputs it just uses the shortcut for those numbers that we have provided.
If you are interested on programming, check out the calc i made its in my blog i made it with a friend of mine.

think of the shortcuts before you start coding that might make ur prog a lot faster and that is what we all need.
\/
\/
\/

chamidilk · Feb 14, 2009

hmmm
gud i also like optimizing progz .....
hv u hd a look on ma 1st prime investigating prog ...
t z a marvellous optimization of prime investigation ....
actually i cn do t verywell bt our newbies wil b confused looking thm @ once ...

cn u pls let me know de link of ur calc .....

mata ewanawada eke source code eka ....
oya java dannawada ???
mamath java walin calc ekak haduwa .....

[email protected]

chamidilk · Feb 14, 2009

marai ah eeee calc eka
aiye mata eke source eka e-mail karannako
eka VB walinda haduwe ??????

madurax86 · Feb 14, 2009

chamidilk said:
meke 1 prime ekak widiyata ganne naha
anika even numbers >2 wil nt b processed

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    int isprime;
    cin>>n;
    isprime=true;
    i=abs(n); //neglect negative numbers
    n=i;
    while (i>2) {
          [B]if(n%2==0){isprime=-1;break;}[/B]
          i--;
          if (n%i==0) {isprime=false; break;} ;
          }         
    if (isprime==1&&n!=1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

sure i did check even numbers but dude y put the check inside the while loop ??? this will be slow as my original code

put it like this to get it faster

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    int isprime;
    cin>>n;
    isprime=1;
    i=abs(n); //neglect negative numbers
    n=i;
    if (n%2==0 && n!=2) isprime=-1;
    while (i>2 && isprime==1) {
          i--;
          if (n%i==0) {isprime=0; break;} ;
          }         
    if (isprime==1&&n!=1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

madurax86 · Feb 14, 2009

chamidilk said:
marai ah eeee calc eka
aiye mata eke source eka e-mail karannako
eka VB walinda haduwe ??????

yea fully VB, graph supports graphical differentiation and integration ;p mage pixu wada mona aiya da ane man 2008 AL mora ringa gana zscore madi UCSC yanawa hambunoth

source eka denam commercial wada ba

chamidilk · Feb 14, 2009

please

madurax86 said:

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    int isprime;
    cin>>n;
    isprime=true;
    i=abs(n); //neglect negative numbers
    n=i;
    while (i>2) {
          [B]if(n%2==0){isprime=-1;break;}[/B]
          i--;
          if (n%i==0) {isprime=false; break;} ;
          }         
    if (isprime==1&&n!=1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

sure i did check even numbers but dude y put the check inside the while loop ??? this will be slow as my original code

put it like this to get it faster

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int i,n;
    int isprime;
    cin>>n;
    isprime=1;
    i=abs(n); //neglect negative numbers
    n=i;
    if (n%2==0 && n!=2) isprime=-1;
    while (i>2 && isprime==1) {
          i--;
          if (n%i==0) {isprime=0; break;} ;
          }         
    if (isprime==1&&n!=1) cout<<"Prime"<<endl; else cout<<"Not prime"<<endl;  

    system("PAUSE");
    return EXIT_SUCCESS;
}

yes i agree
mata arake source eka e-mail karannako

madurax86 · Feb 14, 2009

chamidilk said:
yes i agree
mata arake source eka e-mail karannako

source eka 20MB witara wenawa man heta dihata mage yaluwagen ahala upload karanam kamak na ne

truth4L · Feb 14, 2009

onna java num podi help ekak denna tibba...

C gena melo deyak danne nehe :no:

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