Program to print all prime numbers btw 1 to 100

C Program to print all prime numbers btw 1 to 100..
pls explain the program: What is if(p)??

Code
  1. #include

    2. 

  2. #include

    3. 

  3. int main()

    4. 

  4. {

    5. 

  5.  int num,n,div,p;

    6. 

  6.  printf("Enter any number: ");

    7. 

  7.  scanf("%d", &num);

    8. 

  8.  for(n=2; n<=num; n++)

    9. 

  9.  {

    10. 

  10.   for(div=2; div  {

    11. 

  11.    if(n%div==0)

    12. 

  12.    {

    13. 

  13.      p=0;

    14. 

  14.      break;

    15. 

  15.    }

    16. 

  16.    p=1;

    17. 

  17.   }

    18. 

  18.   if(p)

    19. 

  19.     printf("    %d",n);

    20. 

  20.  }

    21. 

  21.  getch();

    22. 

  22.  

    23. 

  23. }
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Showing Answers 1 - 6 of 6 Answers

shweta gupta

  • Jun 25th, 2014
 

Code
  1. #include<iostream>

    2. 

  2. using namespace std;

    3. 

  3. int main(){

    4. 

  4. for(int i=1;i<=100;i++){

    5. 

  5.         int flag=0;

    6. 

  6.         if(i/2==0||i/2==1)

    7. 

  7.         {

    8. 

  8.                 cout<<"prime"<<i<<endl;

    9. 

  9.                 continue;

    10. 

  10.         }

    11. 

  11.         for(int j=2;j<=i/2;j++){

    12. 

  12.                 if(i%j==0){flag=0; break;}

    13. 

  13.                 else flag=1;

    14. 

  14.         }

    15. 

  15.         if(flag){

    16. 

  16.                 cout<<"prime "<<i<<endl;

    17. 

  17.         }

    18. 

  18. }

    19. 

  19.  

    20. 

  20. return 0;

    21. 

  21. }


Code
  1. #include<iostream>

    2. 

  2. using namespace std;

    3. 

  3. int main(){

    4. 

  4. for(int i=1;i<=100;i++){

    5. 

  5.         int flag=0;

    6. 

  6.         if(i/2==0||i/2==1)

    7. 

  7.         {

    8. 

  8.                 cout<<"prime"<<i<<endl;

    9. 

  9.                 continue;

    10. 

  10.         }

    11. 

  11.         for(int j=2;j<=i/2;j++){

    12. 

  12.                 if(i%j==0){flag=0; break;}

    13. 

  13.                 else flag=1;

    14. 

  14.         }

    15. 

  15.         if(flag){

    16. 

  16.                 cout<<"prime "<<i<<endl;

    17. 

  17.         }

    18. 

  18. }

    19. 

  19.  

    20. 

  20. return 0;

    21. 

  21. }

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Rajkumar Yonzan

  • Feb 24th, 2017
 

// Wap to display all prime number from 1 to 100. //

#include
#include
void main()
{
int i,j,n;
for(n=1;n<=100;n++)
{
i=0;
for(j=1;j<=n;j++)
{
if(n%j==0)
i++;
}
if(i==2)
printf("
%d",n);
getch();
}
}

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jbode

  • Mar 8th, 2017
 

To answer the specific question, "if(p)" is the same thing as "if (p == 1)" or "if (p != 0)". The variable "p" is being used as a flag to indicate whether the current candidate number ("n") is prime or not. Thats being determined by using the modulo operator %. If "a % b == 0", then "a" is evenly divisible by "b". So the program performs "n % div" for all values of "div" from 2 to ... something (that part of the code appears to be missing). If "n % div != 0" for all values of "div", then the number is prime and "p" is set to 1 (true). If "n % div == 0" for any value of "div", then the number is "not" prime and "p" is set to 0 (false). 

Code
  1.  

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