C interview questions and answers

• What will print out?main()
  { 
  char *p1=“name”; 
  char *p2;
  p2=(char*)malloc(20);
  memset (p2, 0, 20);
  while(*p2++ = *p1++); 
  printf(“%sn”,p2);
  
  }
  
  Answer:empty string.


• What will be printed as the result of the operation below:
  

  main()
  { 
  int x=20,y=35;
  x=y++ + x++;
  y= ++y + ++x; 
  printf(“%d%dn”,x,y);}

  
  Answer : 5794


• What will be printed as the result of the operation below:
  

  main()
  {
  int x=5;
  printf(“%d,%d,%dn”,x,x< <2,x>>2);}

  
  Answer: 5,20,1


• What will be printed as the result of the operation below:
  

  #define swap(a,b) a=a+b;b=a-b;a=a-b;void main()
  {
  int x=5, y=10;
  swap (x,y);
  printf(“%d %dn”,x,y);
  swap2(x,y);
  printf(“%d %dn”,x,y);
  }
  
  int swap2(int a, int b)
  {
  int temp;
  temp=a;
  b=a;
  a=temp;
  return 0;
  
  }

  
  Answer: 10, 5
  10, 5


• What will be printed as the result of the operation below:
  

  main()
  {
  char *ptr = ” Cisco Systems”;
  *ptr++; printf(“%sn”,ptr);
  ptr++;
  printf(“%sn”,ptr);}

  
  Answer:Cisco Systems
  isco systems


• What will be printed as the result of the operation below:
  

  main()
  {
  char s1[]=“Cisco”;
  char s2[]= “systems”;
  printf(“%s”,s1);
  } 

  
  Answer: Cisco


• What will be printed as the result of the operation below:
  

  main()
  {
  char *p1;
  char *p2;    p1=(char *)malloc(25);
  p2=(char *)malloc(25);
  
  strcpy(p1,”Cisco”);
  strcpy(p2,“systems”);
  strcat(p1,p2);
  
  printf(“%s”,p1);
  
  }

  
  Answer: Ciscosystems


• The following variable is available in file1.c, who can access it?:
  

  
  

  static int average;

  
  

  
  Answer: all the functions in the file1.c can access the variable.


• WHat will be the result of the following code?
  

  #define TRUE 0 // some codewhile(TRUE)
  {
  
  // some code
  
  }

  
  Answer: This will not go into the loop as TRUE is defined as 0.


• What will be printed as the result of the operation below:
  

  int x;
  int modifyvalue()
  {
  return(x+=10);
  }int changevalue(int x)
  {
  return(x+=1);
  }
  
  void main()
  {
  int x=10;
  x++;
  changevalue(x);
  x++;
  modifyvalue();
  printf("First output:%dn",x);
  
  x++;
  changevalue(x);
  printf("Second output:%dn",x);
  modifyvalue();
  printf("Third output:%dn",x);
  
  }

  
  Answer: 12 , 13 , 13


• What will be printed as the result of the operation below:
  

  main()
  {
  int x=10, y=15;
  x = x++;
  y = ++y;
  printf(“%d %dn”,x,y);}

  
  Answer: 11, 16


• What will be printed as the result of the operation below:
  

  main()
  {
  int a=0;
  if(a==0)
  printf(“Cisco Systemsn”);
  printf(“Cisco Systemsn”);}

  
  Answer: Two lines with “Cisco Systems” will be printed.