C programming

Question 1

How to find string length

Answer 1

strlen(char *);

Question 2

C++: How pair is used?

Answer 2

pair numCharPair;
numCharPair.first = 78;
numCharPair.second = 'M';
- or -
numCharPair = make_pair(78, 'M');

Question 3

C++: How to get current working directory from a running linux program?

Answer 3

getcwd(char[1024], 512);

Question 4

What is C++ static_cast<>

Answer 4

static_cast<> can be used to convert pointers from base class to parent class & vice versa. static_cast<> between unrelated class pointers is compilation error.

Question 5

How to compile C++ program with C++11 support?

Answer 5

g++ -std=c++11 xyz.cpp

Question 6

Show an example of pointer to a member function (method).

Answer 6

class Foo { public: int func(char x) { return 7;}

int (Foo::*fptr)(char);
fptr = &Foo::func;
Foo   obj;
// Call below,
(obj.*func)('A');
Foo *p = &obj;
// Call below,
(p->*func)('K');

Question 7

C++: Can a static mmbr function call non-static mmbr function?

Answer 7

A static member function cannot access any non-static members. It is a compilation error.

Question 8

Give example of typedef usage.

Answer 8

typedef existing_typeName new_typeName;

typedef unsigned int unsINT;

It is used to give more descriptive name to complicated types.

typedef struct student {
int roll_num;
char name[32];
} st;

st p1, p2;

Question 9

What is a Makefile ‘pattern rule’?

Answer 9

It uses % wildcard. I can only be used in target : dependency line, never in action lines.

%.wc : %.x
wc -l $.x > $.wc

all : a.x b.x c.x
This produces line number files for each .x file
$ in the action line matches with the stem of match in pattern.

Question 10

Makefile: Give an example of wildcard function usage.

Answer 10

HDRS = $(wildcard src/*.h)

HDRS is a list of header files in src directory.

Question 11

Makefile: Give an examplle of patsubst function usage.

Answer 11

HDRS = $(patsubst %.cpp, %.hpp, a.cpp b.cpp x.cpp)
HDRS is
a.hpp b.hpp x.hpp

Question 12

C++: Does catch block do type conversion?

Answer 12

No.
Exception catch block does not do type conversion.
catch(double d)
will not catch “int” exception.

Question 13

How do you create a unique_ptr?

Answer 13

unique_ptr<int>  ptr1(new int);
unique_ptr<int>  ptr2(new int(47);
unique_ptr<int>  ptr3 = make_unique<int>(47);
unique_ptr<Person> p1(new Person("khan", 45));

unique_ptr<Person> p2 = make_unique<Person>("Khan", 45);