Top C C++ Errors Interview Questions

Q – 1 Explain what is macro in c?
Difference between single linked list & double linked list what is fifo & lifo?
what is stack & queue?

Ans- Macros are preprocessor directives that are defined using #define directive. Macros consist of two parts Macro_Name, & Macro_Substitution_Text.

Before the source code gets complied, the preprocessor will check for the presence of macros. & wherever it found that macro simply replaces that macros with substitution text.

Macros are not Type Safe.

Q – 2 Display this kind of output on screen.
1
0 1
1 0 1
3. Display this kind of output on screen.
1
1 0
1 0 1
4. Display this kind of output on screen.
1
1 0
1 0 1
5.Display this kind of output on screen.
1
2 3
4 5 6
7 8 9 10

Ans- void main()
{
int i,j;
for(i=0;i<=2;i++) { for(j=2;j>i;j–)
printf(” “);
for(j=1;j<(i+1);j++)
{
printf(“%d”,mod(j-i));
}
printf(“/n”);
}
getch();
}

——————————void main()
{
int i,j;
for(i=0;i<=2;i++) { // for(j=2;j>i;j–)
// printf(” “);
for(j=1;j<(i+1);j++)
{
printf(“%d”,mod(i-j));
}
printf(“/n”);
}
getch();
}
——————————–
void main()
{
int i,j;
for(i=0;i<=2;i++) { //for(j=2;j>i;j–)
// printf(” “);
for(j=1;j<(i+1);j++)
{
printf(“%d”,mod(j-i));
}
printf(“/n”);
}
getch();
}
————————-
void main()
{
int i,j,k=1;
for(i=0;i<=3;i++) { for(j=3;j>i;j–)
printf(” “);
for(j=1;j<(i+1);j++) { k=k+1; printf(“%d”,k); } printf(“/n”); } getch(); }

Q – 3 How to reverse a linked list without using array & -1?

Ans- IS it possible by sorted list???.

Q – 4 Errors are known as?

Ans- It’s a human mistake associated with the program

Q – 5 What is meant for variable not found?

Ans- when u have not declared variable in the main function or any other function but used in the program. example: main() { int i,j;—————-> (iSum not declared)
printf(“enter the value of i and j”);
scanf(“%d%d”,&i,&j);
iSum = i + j;
printf(“The Sum =”,iSum);
getch();
}
In this case iSum will Show a compiler error “Variable not
found”.

Q – 6 What is syntax error?

Ans- synatx error is a compile type error. it will occur when the programmer doesnot follow the standard rules or syntax of programming.

Q – 7 void main()
{
int i=5,y=3,z=2,ans;
clrscr();
printf(“%d”,++i + –z + i++ + –i * ++y);
i=5,y=3,z=2;
ans=++i + –z + i++ + –i * ++y;
printf(“n%d”,ans);
getch();
}

Its output is 37 and 31….
Please explain me why its different
How it works?

Ans- here in first statement

printf(“%d”,++i + –z + i++ + –i * ++y);

argument is : ++i + –z + i++ + –i * ++y.

first it will maintain stack operation like

++y (now fifth, it will execute and, y=4)(top 4)
–i (now fourth, it will execute and, i=6)
(because, last value of i were 7, once i++ were
executed, now –i will less one value in i)(top 3)
i++ (now third, it will execute and, i=6, it will
as it is, its value will for next stack value.)
(top 2)
–z (now second, it will execute and, z=1)(top 1)
++i (first it will execute and, i=6)(top 0)

now (++i + –z + i++ + –i * ++y)
(6+1+6+6*4)=(37)

it is output, say 37,for this printf(“%d”,++i + –z + i++
+ –i * ++y);

Now Let me go with second statement, that is :

ans=++i + –z + i++ + –i * ++y;

here,
first of all ++y will contain the value of variable y=4
++y=4

after this, –i will less the value of variable i, say now
i = 4,
(–i=4),

after this, i++ will execute and, it will not increase the value of variable i, right now, so value of i, say now i = 4, as it is.

after this, –z will less the value of variable z, say now z = 1,
(–z=1)

now, ++i will increase the value of variable i.
Say i = 5.
now value of valiable i in memory is 5.
ans=5+1+5+5*4
ans=5+1+5+20
ans=31……….,

Q – 8 void main()
{
int i=7;
printf(“N= %*d”,i,i);
}

Ans- Its output would be 7,

“%*d”

here * symbol doesn’t affect of operation of %d.

Q – 9 What is run time error?

Ans- An error that occurs during the execution of a program. In contrast, compile-time errors occur while a program is being compiled. Runtime errors indicate bugs in the program or problems that the designers had anticipated but could do nothing about.

For example, running out of memory will often cause a runtime error. A runtime error is a computer error that appears in the form of a message box consisting of a particular code along with its corresponding definitions.

Usually, a user will notice that the computer becomes noticeably slow before a runtime error appears.

After the runtime error message has been displayed and closed, the software that shows this error would normally close or freeze. In some cases, the operating system will reboot.

Q – 10 char* f()
return “hello:”;
void main()
{char *str=f();
}

Ans- str will be a pointer to “hello:”

so on printing str will output hello:

Q – 11 When i use cout or cin call & then either << or >> …..it shows
declaration syntax error…what should i do?
cout<<“anything”; int a; cin>>a;
return 0;?

Ans- If you are using Turbo C complier need to add #include header file.

and If you are using Visual Studio then you need to add

#include
using std namespace;

the above two statements.

Q – 12 Can you explain exceptions?

Ans- An exception is an event, which occurs during the execution of a program, that disrupts the normal flow of the program’s instructions.

Q – 13 Explain difference between c/c++ programing language?
what is necessity of c++ when existing c programing language?

Ans- The main reason is lengthy C programs lose “Global View” and become very difficult to visualize as a single concept.

C++ is an advance than C lang which has more features…

But comparing efficiency C is more efficient than C++

But C++ has more flexibility than C.

Also C++ is both combination of OOP and OBP concepts.

C++ has more features as

1.Object oriented
2.Information hiding
3.Standard Template Library
4.Inheritance
5.Constructors & Destructors
6.Exception Handling
7.Overloading