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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <unistd.h>
  4. #include <sys/types.h>
  5. #include <sys/wait.h>
  6. #include <string.h>
  7.  
  8. void sum_of_digits()
  9. {
  10.     int num, sum = 0, rem;
  11.  
  12.     printf("Enter the number: ");
  13.     scanf("%d", &num);
  14.  
  15.     while (num != 0) {
  16.         rem = num % 10;
  17.         sum += rem;
  18.         num /= 10;
  19.     }
  20.  
  21.     printf("Sum of Digits: %d\n", sum);
  22. }
  23.  
  24. int main(int argc, char *argv[])
  25. {
  26.     pid_t c1, c2;
  27.  
  28.     if (argc > 1 && strcmp(argv[1], "sum") == 0) {
  29.         sum_of_digits();
  30.         return 0;
  31.     }
  32.  
  33.     c1 = fork();
  34.  
  35.     if (c1 == 0) {
  36.         execlp("echo", "echo", "Happy new year", NULL);
  37.         _exit(1);
  38.     }
  39.     else {
  40.         wait(NULL);
  41.  
  42.         c2 = fork();
  43.  
  44.         if (c2 == 0) {
  45.             execlp(argv[0], argv[0], "sum", NULL);
  46.             _exit(1);
  47.         }
  48.         else {
  49.             wait(NULL);
  50.             printf("Parent exiting …good bye....\n");
  51.         }
  52.     }
  53.  
  54.     return 0;
  55. }
  56.  
Success #stdin #stdout 0.01s 5316KB
comments (?)
stdin
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123
stdout
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Happy new year
Enter the number: Sum of Digits: 6
Parent exiting …good bye....
https://ideone.com/sZansM
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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