C interview questions and answers

1. 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.
   
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%dn”,x,y); }

   Answer : 5794
   
3. 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
   
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 %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
   
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
   
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:%dn",x);
        x++;
        changevalue(x);
        printf("Second output:%dn",x);
        modifyvalue();
        printf("Third output:%dn",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 %dn”,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 Systemsn”);
            printf(“Cisco Systemsn”); }

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

Posted in: C