studentVar.name=“smith”;
Structures
- How to print structure variable data?
- printf("%d,%s", studentVar.id, studentVar.name);
Legal operations with structures
- Copy it as a unit
- Assign to it as a unit
- Take it’s address with &
- Access it’s members
Pointers to Structures
- struct student studentVar, *pp;
- pp = &studentVar;
- printf(“student details (%d,%s)\n", (*pp).id, (*pp).name);
- printf(“student details (%d,%s)\n", pp->id, pp->name);
- Notice the above two lines. How the member variables were accessed.
- (*pp).id or pp->id
Array of Structures
struct student{
int id;
char *name;
char *address;
char *cell;
} studentList = {
{100,”name1”,”address1”},
{101,”name2”,”address2”},
{102,”name3”,”address3”}
};
Union
- Union declaration, assignment may look like pretty similar to structures
- Unions are usually used to store data of different data types for the same concept
- All member variables points to the same memory location
- Actually, we are trying to store one value
- But as the data type of the value can differ, hence, we are keeping options
- Usually, the storage will be of the size of the largest data type
- The programmer is responsible to remember and extract the same data type he stored
- For example, you want to store tags. However, tags can be of int, float, or string type
based on context. Then you can declare a union as follows
Union
union tag {
int ival;
float fval;
char *sval;
} u;
Enum
enum DAY {
saturday,
sunday ,
monday,
tuesday,
wednesday,
thursday,
friday
} workday;
enum DAY today = wednesday;
I/O Functions
- Misc
- int ungetc(int c, FILE *fp)
- system("date");
- Storage Management
- void *malloc(size_t n)
- void *calloc(size_t n, size_t size)
- int *ip;
- ip = (int *) calloc(n, sizeof(int));
I/O Functions: Mathematical Functions
- sin(x) x in radian
- cos(x)
- atan2(y,x)
- exp(x)
- log(x) (x>0) , natural
- log10(x) (x>0) , 10 based
- pow(x,y) x to the power y
- sqrt(x)
- fabs(x) absolute value of x
Reference: "The C Programming Language”: Kernighan and Ritchie
Presentation Slides on C and C++
Here, I am listing two presentation slides on C and C++. Yes, I myself have created them. I am planning to improve the slides shortly and create training videos on them (esp. c++ - it needs much work). Have fun.
Lesson 1: Short Notes on C++
This short note is for those who already know C++ and want to
refresh their memory. Beginners can still take a look to get an overall idea.
- Three pillars of object-oriented development: encapsulation, inheritance, and polymorphism.
- C++ supports encapsulation through (user-defined)
classes. Class properties and internal
workings can be hidden from outside world.
- C++ supports polymorphism through overloading, overriding
- C++ supports inheritance by allowing classes to share (extend) the properties and workings of other classes
- Managed C++ is an extension of the C++ language. Managed C++ allows the use of Microsoft's new platform (.Net) and libraries
- How to include header files: #include <iostream> or #include <iostream.h>
- Print in the console: std::cout <<"Hello World!\n"; or cout <<"Hello World!\n"; std::cout << "Number and String together:\t" << 70000;
- Read from the console: std::cin >> response; where response is a variable
- If you do not want to use 'std::' in the previous examples, you can use the statement 'using namespace std;' before
- How to comment: use // to comment single line or use /*c++ code*/ to comment a block
- [ Code commenting is a good practice only when you describe why is the code block than what the block does.]
- C++ is case sensitive
- Keywords, Reserved words: Some words are reserved in C++. You can not use them as variable names.
- Keywords:
asm else new this
auto enum operator throw
bool explicit private true
break export protected try
case extern public typedef
catch false register typeid
char float reinterpret_cast typename
class for return union
const friend short unsigned
const_cast goto signed using
continue if sizeof virtual
default inline static void
delete int static_cast volatile
do long struct wchar_t
double mutable switch while
dynamic_cast namespace template
- Reserved words: And bitor not_eq xor
and_eq compl or xor_eq
bitand not or_eq
- Variable declaration: unsigned int age;
- How to create aliases:
typedef unsigned short int USHORT;
- C++ Escape characters:
\a Bell (alert)
\b Backspace
\f Form feed
\n New line
\r Carriage return
\t Tab
\v Vertical tab
\' Single quote
\" Double quote
\? Question mark
\\ Backslash
\000 Octal notation
\xhhh Hexadecimal notation
- Define constants:
#define numberOfContinents 7
- Enumerated constants:
enum WeekDays { Monday, Tuesday,
Wednesday, Thursday, Friday};
WeekDays day;
Advanced Concepts in C++
C++ Syntax: in brief
Sorry, this will make sense only if you want to refresh your memory on C++ syntax.
cout << "Enter two integers:" << endl; // output to screen
cin >> n >> m;
// Note: Using endl prints out a newline and flushes the output buffer.
cout << "number of digits in char: " << numeric_limits::digits << '\n';
if (n > m) { // if n is bigger than m, swap them
int temp = n; // declare temp and initialize it
n = m; // assign value of m to n
m = temp; // assign value of temp to m
}
long iii = i; // implicit conversion from int to long
iii = long(i); // explicit conversion from int to long
for (double d = 1.1; d <= 9.9; d += 0.2) sum += sin(d);
using namespace std;
#include
int main() {
using namespace std;
}
const int mxdigits = 999500;
int* p = &n;
int m = 200;
*p = m;
double* tryd = new double (x);
unsigned int jj = ii;
cout.width(2);
cout << i;
struct point2d {
char nm;
float x;
float y;
};
point2d pt2 = { 'A', 3.14, -38 };
union val {
int i;
double d;
char c;
};
double* tmv = new double[n];
int n = atoi(argv[1]); // first integer is assigned to n
int* local = new int;
*local = 555;
namespace Vec {
const int maxsize = 100000; // a const number
double onenorm(double*, int); // L 1 norm
}
double Vec::onenorm(double* v, int size) {
}
std::cout <<"Approx root near 7.7 by newton method is: " << root << '\n';
---
std::srand(time(0)); // seed the random number generator
for (int i = 0; i< n; i++) dp[i] = std::rand()%1000;
std::sort(dp, dp+n);
---
double d = - 12345.678987654321;
cout.setf(ios_base::scientific, ios_base::floatfield); // scientific format
cout.setf(ios_base::uppercase);
cout.width(25);
cout.precision(15);
cout.setf(ios_base::left, ios_base::adjustfield); // adjust to left
cout << d << "\n";
--------
double sum(int num, ...);
va_list argPtr;
va_start(argPtr, num); // initialize argPrt. num is the last known argument
double sum = 0;
for( ; num; num--) {
sum += va_arg(argPtr, double); // argument of type double is returned
}
va_end(argPtr); // deallocate stack pointed to by argPtr
return sum;
--
struct point2d {
double x;
double y;
friend double norm(point2d p) { // a friend
return sqrt(p.x*p.x + p.y*p.y); // distance to origin
}
};
----
class triangle {
point2d* vertices;
public:
triangle(point2d, point2d, point2d); // constructor
~triangle() {
} // destructor
double area() const; // a function member
};
----
class triple { // a triple of numbers
float* data;
public:
triple(float a, float b, float c); // constructor
~triple() { } // destructor, also defined here
friend triple add(const triple&, const triple&); // add is a friend
};
inline triple::triple(const triple& t) {
data = new float [3];
for (int i = 0; i < 3; i++) data[i] = t.data[i];
}
-----
operator overloading
class Cmpx { // class for complex numbers
private:
double re; // real part of a complex number
double im; // imaginal part of a complex number
public:
Cmpx(double x = 0, double y = 0) { re =x; im =y; } // constructor
Cmpx& operator+=(Cmpx); // operator +=, eg z1 += z2
Cmpx& operator-=(Cmpx); // operator -=, eg z1 -= z2
Cmpx& operator++(); // prefix, z1 = ++z
Cmpx operator++(int); // postfix, z1 = z++
friend Cmpx operator*(Cmpx, Cmpx); // binary *, z = z1 * z2
friend std::ostream& operator<<(std::ostream&, Cmpx); // operator <<
friend std::istream& operator>>(std::istream&, Cmpx&); // operator >>
};
----------------
template class Vcr {
int lenth; // number of entries in vector
T* vr; // entries of the vector
public:
Vcr(int, T*); // constructor
Vcr(const Vcr&); // copy constructor
~Vcr(){ delete[] vr; } // destructor
};
// partial specialization
template class Vcr< complex > {
int lenth; // number of entries in vector
complex* vr; // entries of the vector
public:
Vcr(int, complex*); // constructor
Vcr(const Vcr&); // copy constructor
~Vcr(){ delete[] vr; } // destructor
};
// complete specialization
template<>
class Vcr< complex > {
int lenth; // number of entries in vector
complex* vr; // entries of the vector
public:
Vcr(int, complex*); // constructor
Vcr(const Vcr&); // copy constructor
~Vcr(){ delete[] vr; } // destructor
};
----------
complex aa = complex(3, 5);
---
list nodes; // a list of integers for nodes
nodes.push_front(10); // add 10 at the beginning
nodes.push_back(5); // add 5 at the end
nodes.pop_back(); // remove last element
nodes.remove(10); // remove element 10
for (list::iterator j = nodes.begin(); j != nodes.end(); j++)
cout << *j << " "; // *j is the element at position j
nodes.sort();
nodes.unique();
nodes.reverse();
nodes.insert(i, 2); // insert before element that i refers to
nodes.insert(i, 5, 7); // insert 5 copies of 7
nodes.erase(i);
ft.merge(sd); // ft has the merged list, sd will be empty
list::iterator ii = find(ft.begin(), ft.end(), 5.5);
sd.splice(sd.begin(), ft, ii);
----
VECTOR
std::vector vi(10);
for (int i = 0; i < 10; i++) vi[i] = (i-5)*i;
std::sort(vi.begin(),vi.end());
std::unique(vi.begin(),vi.end());
-----
C++ Concepts and Syntax
Not really for the beginners. If you had experience working with C++ in the past, then taking a look at this short-note will help to recover your knowledge in C++.
Multiple inheritance means that one subclass can have more than one superclass. This enables the subclass to inherit properties of more than one superclass and to ``merge'' their properties.
char *strp; /* strp is `pointer to char' */
*strp = 'a'; /* A single character */
A pointer to characters can be used to point to a sequence of characters
Class Structure:
class Foo {
// private as default ...
public:
// what follows is public until ...
private:
// ... here, where we switch back to private ...
public:
// ... and back to public.
};
Struct:
class Struct {
public: // Structure elements are public by default
// elements, methods
};
Method definition - outside of the class
void Point::setX(const int val) {
_x = val;
}
void Point::setY(const int val) {
_y = val;
}
Access a method:
apoint.setX(1); // Initialization
Inheritance:
class Point3D : public Point {}
C++ has two types of inheritance: public and private. By default, classes are privately derived from each other
You can inherit as private, protected, public. Private members always come as private in the subclass. Public members of the super class come to the subclass according/(as) to the inheritance type
Multiple Inheritance:
class DrawableString : public Point, public DrawableObject {}
Virtual Function in C++
You can use the keyword 'virtual' before a function declaration to make the function virtual. Subclasses to these class can define the function as they want. It still remains virtual in the subclasses.
http://www.codersource.net/published/view/325/virtual_functions_in.aspx
-- will update and add later
Reference: http://gd.tuwien.ac.at/languages/c/c++oop-pmueller/tutorial.html
C++ Constructor Subclass Base Class
It's better that you clearly understand these
Are C++ Templates Slow?
According to: http://yosefk.com/c++fqa/templates.html#fqa-35.10, C++ Templates are slow.
Though theoretically, templates can be as efficient as straightforward code or more efficient than straightforward code. However, commercial compilers don't optimize templates code in that level. So practically templates are slower. Also, some other complexities may arise while using templates.
FAQs about templates http://yosefk.com/c++fqa/templates.html
Great resource to review C++
C++ Code Examples
Transform binary representation into integral number using bitset
Use bitset with enum together
Call member function for each element in vector
Print minimum, maximum, and sum of the valarray
valarray slice
valarray with double value inside
Sort objects stored in deque
Use sorting criterion in sort function
Read file content
Presentation Slides on C and C++
Here, I am listing two presentation slides on C and C++. Yes, I myself have created them. I am planning to improve the slides shortly and create training videos on them (esp. c++ - it needs much work). Have fun.