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.

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