apps. on C

C interview questions
1.What will print out?
main()
{
char *p1=“name”;
char *p2;
p2=(char*)malloc(20);
memset (p2, 0, 20);
while(*p2++ = *p1++);
printf(“%s\n”,p2);
}
Answer:empty string.
2.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%d\n”,x,y);
}
Answer : 5794
3.What will be printed as the result of the operation below:
main()
{
int x=5;
printf(“%d,%d,%d\n”,x,x< <2,x>>2);
}
Answer: 5,20,1
4.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 %d\n”,x,y);
swap2(x,y);
printf(“%d %d\n”,x,y);
}
int swap2(int a, int b)
{
int temp;
temp=a;
t=a;
a=temp;
return 0;
}
Answer: 10, 5

5.What will be printed as the result of the operation below:
main()
{
char *ptr = ” Cisco Systems”;
*ptr++; printf(“%s\n”,ptr);
ptr++;
printf(“%s\n”,ptr);
}
Answer:Cisco Systems

6.What will be printed as the result of the operation below:
main()
{
char s1[]=“Cisco”;
char s2[]= “systems”;
printf(“%s”,s1);
}
Answer: Cisco
7.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
8.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.
9.WHat will be the result of the following code?
#define TRUE 0 // some code
while(TRUE)
{ // some code
}
Answer: This will not go into the loop as TRUE is defined as 0.
10.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:%d\n",x);
x++;
changevalue(x);
printf("Second output:%d\n",x);
modifyvalue();
printf("Third output:%d\n",x);
}
Answer: 12 , 13 , 13
11.What will be printed as the result of the operation below:
main()
{
int x=10, y=15;
x = x++;
y = ++y;
printf(“%d %d\n”,x,y);
}
Answer: 11, 16
12.What will be printed as the result of the operation below:
main()
{
int a=0;
if(a==0)
printf(“Cisco Systems\n”);
printf(“Cisco Systems\n”);
}
Answer: Two lines with “Cisco Systems” will be printed.
13.Which of the following is illegal
(a)void v;
(b)void *v;
(c)void **v;
(d)all are legal
Answer: void v
14.What is the output ?
#define int INTEGER /*line1*/
#define INTEGER int /*line 2*/
main()
{
INTEGER p=10; /*line 5*/
printf("%d",p);
}
o/p?
(a)compiler error at line 1
(b)compiler error at line 2
(c)compiler error at line 5
(d)No error,prints 10
Answer: c
15.main()
{
int counter=1;
for(;;)
{
counter++;
if(counter>9)
break;
}
Answer: 9 times loop executes.