review of c++

Dinesh Kumar Ram(PGT CS)

REVIEW OF C++


Contents

1.C++ Basics2.Data Handling3.Operators and

Expressions4.Flow of Control5.Console I/o

Operators

6.Arrays7.User defined

Functions8.Standard Library

Functions9.Structures

Indicates very important topics


C++ Character Set

C++ tokens

Keywords Identifiers Constants


DATA HANDLING

int

float

char

double

Basic Data Types in C++

1. 2 bytes 2. Eg. int a;

1. 4 bytes 2. Eg. float a;

1. 8 bytes 2. Eg. double a;

1. 1 bytes 2. Eg. char a;


DATA TYPE MODIFIERS

1. signed 2. unsigned 3. short 4. long

Type Typical Bit Widthchar 1byte

unsigned char 1bytesigned char 1byteint 2bytes

unsigned int 2bytessigned int 4bytes

short int 2bytesunsigned short int 2 bytes

signed short int 2 byteslong int 4bytes

signed long int 4bytesunsigned long int 4bytes

float 4bytes

double 8bytes

long double 10 bytes


Derived Data Types

Arrays- An array is a data structure which allows a collective name to be given to a group of elements which all have the same type. An individual element of an array is identified by its own unique index (or subscript). Eg: double balance[10];

Functions- A function is a group of statements that together perform a task. Every C++ program has at least one function which is main(), and all the most trivial programs can define additional functions.

Pointer- pointer is a variable whose value is the address of another variable. Like any variable or constant, you must declare a pointer before you can work with it. The general form of a pointer variable declaration is:type *var-name; Eg. int *t;

Reference - A reference variable is an alias, that is, another name for an already existing variable. Once a reference is initialized with a variable, either the variable name or the reference name may be used to refer to the variable.int i = 17; int& r = i;


User-Defined Derived Data Types - class

1. Class represents a group of similar objects

2. To define a class in c++, keyword class is used.

3. It has two types of members. By default they are private.

class Box{ public: double length; // Length of a box double breadth; // Breadth of a box double height; // Height of a box double getVolume(void) { return length * breadth * height; }};

Data members

Members Function


2. Structure

1. C++ arrays allow you to define variables that combine several data items of the same kind but 2. structure is another user defined data type which allows you to combine data items of different kinds.3. Structures are used to represent a record,

struct Books{ char title[50]; char author[50]; char subject[100]; int book_id;}book;

202 bytes allocated for book

Members

Stucture variable

50 50 100 2


3. Union

1. A union is a user-defined data or class type that, at any given time, contains only one object from its list of members (although that object can be an array or a class type).

union Books{ char title[50]; char author[50]; char subject[100]; int book_id;}book;

Members

100 bytes allocated for book


4. Enumeration

1. An enumeration is a user-defined type consisting of a set of named constants called enumerators.

2. It is another way of defining integer constant

Values of enum constants

enum MyEnumType { ALPHA, BETA, GAMMA }; ALPHA has a value of 0, BETA has a value of 1, and GAMMA has a value of 2.

enum FooSize { SMALL = 10, MEDIUM = 100, LARGE = 1000 };


OPERATORS AND EXPRESSIONS

An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations.

C++ is rich in built-in operators and provides following type of operators:1. Arithmetic Operators2. Relational Operators3. Logical Operators4. Bitwise Operators5. Assignment Operators6. Misc Operators


OPERATOR PRECEDENCE

Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators have higher precedence than others

Category Operator Associativity Postfix () [] -> . ++ - - Left to right Unary + - ! ~ ++ - - (type)* & sizeof Right to left

Multiplicative * / % Left to right Additive + - Left to right Shift << >> Left to right Relational < <= > >= Left to right Equality == != Left to right Bitwise AND & Left to right Bitwise XOR ^ Left to right Bitwise OR | Left to right Logical AND && Left to right Logical OR || Left to right Conditional ?: Right to left Assignment = += -= *= /= %=>>= <<= &= ^= |= Right to left

Comma , Left to right


TYPE CONVERSION

Implicit or Automatic type conversion

Implicit type conversion is performed by the compiler without programmers intervention

Eg: cout<<(7+4.5);

Explicit or Type casting

Explicit conversion is user-defined that forces an expression to be of specific type.

Eg: cout<<7+(int)4.5;

It is the process of converting one type into another. In other words converting an expression of a given type into another is called type casting


FLOW OF CONTROLBy Default, the flow of control in a c++ program is sequential

Looping statements

Jump statements

Conditional statement

while

do-while

for

goto break continueexit()

If

If..else

switch

?:


Conditional statement - Examples

if(age>=18) cout<< “Major”;If(age< 8)

cout<<“Minor”;

if(age>=18)cout<< “Major”;

elsecout<<“Minor”;

if(num>0)cout<< “+ve no”;

else if(num<0)cout<<“-ve no”;

elsecout<<“zero”;

If…else statements

Switch statement Using ?: operatorSwitch(week_day){

case 1: cout<<“Mon”; break;case 2: cout<<“tue”; break;case 3: cout<<“Wed”; break;case 4: cout<<“Thus”; break;case 5: cout<<“Fri”; break;case 6: cout<<“sat”; break;case 7: cout<<“sun”; break;default: cout<<“invalid i/p”;

};

1. (age>=18)? cout<<“Major”: cout<<“Minor”;

2. (num<0)? cout<<“+ve”: (num>0)? cout<<“-

ve”:cout<<“zero”;


Looping statements - Examples

num=10;While(num>=0){

cout<<num<<“:”;num--;

}

num=10;do{

cout<<num<<“:”;num--;

}while(num>=0);

for(num=10;num>=0;num--)cout<<num<<“:”;

while- Entry controlled loop do..while- Exit controlled loop

for – Entry controlled loop


Jump statements- Examples

Goto statement1. Unconditional jump stmt. 2. Transfers the control to the label

mentioned.3. Two types: forward goto and

backward goto stmt.4. Forward goto skips the stmts.

between the goto and label.5. Backward goto repeats the

stmts. In between goto and label.

6. Example of a backward gotoEG:int a=10;L1: a++;cout<<a<<“:”;goto L1;

7. Example for a forward gotoEG:int a=10;goto L1;a++;L1:cout<<a<<“;”;

NOTE:

CARE MUST BE TAKEN WHEN GOTO STMTS ARE USED IN A PROGRAM.AVOID GOTO STMTS. IN A PRGM.


Jump statements- break and continue

break; stmt1. Unconditional jump stmt.2. Usually used in a loop or switch

stmt.3. When cntl reaches break stmt. ,

the rest of the stmts. in the loop or switch is ignored and jumps over to the stmt following the loop.

4. EG:for( int i=0;i<10;i++){

if(a==5)break;cout<<a<<“:”;

}cout<<“End”;

continue; stmt.1. Unconditional jump stmt.2. Usually found in a loop3. Continue skips the rest of the

lines in a loop and moves to the next iteration.

4. EG:for(int i=0;i<10;i++){

if(a==5)continue;cout<<a<<“:”;

}cout<<“End”;


Lets revise some of programs based on looping statements

1. Program to print the sum of n natural numbers

2. Program to print following pattern:a) 1234 b) 1

123 1212 1231 1234

3. Program to find the following sum of series


Console I/O Operators

Unformatted I/O Operations1. get()- used to read a single

character from the i/p device.2. put()- used to print a single

character on to the console.3. getline()- reads array of

characters that ends with ‘\n’ by default, or until the limit is reached.

4. write()- prints the array of characters on to the console.

Formatted I/O Operations1. width()- specifies the required

number of fields to be used while displaying the o/p.

2. precision()- specifies the number of digits to be displayed after the decimal point.

3. fill()- specifies a charater to be filled in the unused area of a field

4. setf() sets the format flag that controls the o/p data.


ARRAYSARRAYS - An array is a variable that holds multiple values of the same type. SYNTAX: data_type array_name[size];

Array Initialization for One – Dimensional Arrays

int a[ ]={10,20,30};

char a[ ] = “Hello”; or char a[ ]={‘H’,’e’,’l’,’l’,’o’,’/0’};

Array Initialization for 2 Dimensional Array

int a[][]={ {1,2,3},{1,4,5},{1,6,7};

char name[][] ={ “apple”,”Mango”,”Orange”};


Lets revise some of the programs in 1 D arrays

1. Program to find the sum of n elements in array

2. Program to add odd elements in array

3. Program to swap elements at even position with the elements at odd position

in 1- D array

4. Program to search an element in 1 D array

5. Program to add prime numbers in a 1 D array

6. Program to count number of vowels and consonants in a sentence

7. Program to count no of words in 1 D array

8. Program to reverse a string and checking whether it is a palindrome or not


Programs in 2 D arrays

1. Program to find the sum of diagonal elements in a matrix

2. Program to find the row sum and column sum in a matrix

3. Program to find the largest and second largest element in a matrix

4. Program to add, subtract and multiply matrices

5. Program to sort a array of names alphabetically

6. Program to find the transpose of a matrix


FUNCTIONSA function is a group of statements that together perform a task. Every C++ program has at least one function which is main(), and all the most trivial programs can define additional functions.

A function declaration tells the compiler about a function's name, return type, and parameters.

A function definition provides the actual body of the function. To use a function, you will have to call or invoke that function.

include <iostream> int max(int num1, int num2); int main () {int a = 100, b = 200,ret;

ret = max(a, b);

cout << "Max value is : " << ret << endl; return 0; }

int max(int num1, int num2) {

int result; if (num1 > num2) result = num1; else result = num2; return result;

}


Whenever function definition appears before the function call, there is no need of function prototype.

include <iostream> int max(int num1, int num2); int main () {int a = 100, b = 200,ret;

ret = max(a, b);

cout << "Max value is : " << ret << endl; return 0; }

int max(int num1, int num2) {

int result; if (num1 > num2) result = num1; else result = num2; return result;

}


DIFFERENCE BETWEEN CALL BY VALUE AND CALL BY REFERENCE

Call by Value1. In call by value, A separate copy of

formal parameter is created.2. Values of actual parameter are copied

on to the formal parameter.3. Any change made to the formal

parameter will not effect the actual parameter

Call by reference1. In call by reference, the address of

the actual parameter are passed as argument during a call.

2. No separate copy of formal parameter is created. Act as a alias name to the actual argument.

3. Any change made to the formal parameter will reflect the original copy.

void display(int a,int &b){

a=a+10;b=b+10;

}

void main(){

int a=40,b=20;display(a,b);cout<<a<<“::”<<b;

}


Default Arguments

1. Default values for the arguments can be given to the functions2. By default, the number of actual parameters must match with the number of

formal parameters.3. But while giving default values to the arguments, there is no such restrictions.

The missing arguments will take up the default values.

EXAMPLE:Consider the following prototypeint my_func(int a, int b, int c=12);

The following are the valid function calls:result = my_func(1, 2, 3);result = my_func(1, 2);


Programs based on User – Defined Functions

1. Write a program using function which accept two integers as an argument and

return its sum. Call this function from main( ) and print the results in main( ).

2. Write a function that receives two numbers as an argument and display all

prime numbers between these two numbers. Call this function from main( ).

3. Write a function called zero_small() that has two integer arguments being

passed by reference and sets the smaller of the two numbers to 0. Write the

main program to access the function.


Standard library function

Operations on files:remove-Remove file (function )Rename- Rename file (function )

Character input/output:fgetc-Get character from stream (function )fgets-Get string from stream (function )fputc-Write character to stream (function )fputs- Write string to stream (function )getc-Get character from stream (function )getchar-Get character from stdin (function )gets-Get string from stdin (function )putc-Write character to stream (function )putchar-Write character to stdout (function )puts-Write string to stdout (function )ungetc-Unget character from stream (function )

stdio.h


FunctionsCopying:memcpy-Copy block of memory (function )memmove-Move block of memory (function )strcpy-Copy string (function )strncpy- Copy characters from string (function )

Concatenation:strcat-Concatenate strings (function )strncat-Append characters from string (function )

Comparison:memcmp-Compare two blocks of memory (function )strcmp-Compare two strings (function )

Searching:memchr-Locate character in block of memory strchr-Locate first occurrence of character in string strcspn-Get span until character in stringOther:memset-Fill block of memory strerror-Get pointer to error message string strlen-Get string length (function )

string.h


FunctionsString conversion:atof-Convert string to double atoi-Convert string to integer atol-Convert string to long integer atoll-Convert string to long long integer strtod-Convert string to double strtof-Convert string to float strtol-Convert string to long integer strtold-Convert string to long double

Pseudo-random sequence generation:

rand- Generate random number (function )srand-Initialize random number generator (function )

Dynamic memory management:calloc- Allocate space for array in memory free-Deallocate space in memory malloc- Allocate memory block realloc-Reallocate memory block

stdlib.h

Trigonometric functions:cos-Compute cosine sin-Compute sine tan-Compute tangent acos-Compute arc cosine asin-Compute arc sine atan-Compute arc tangent

Exponential and logarithmic functions:exp-Compute exponential function log-Compute natural logarithm

Power functionspow-Raise to power sqrt-Compute square root

Rounding, absolute value and remainder functions:ceil-Round up value fabs-Compute absolute value floor-Round down value fmod-Compute remainder of division

math.h


Programs- Standard Library Function

1. Write a program which input principal, rate and time from user and calculate

compound interest

2. Write a program to compute area of triangle. Sides are input by user.

3. Write a program to check character entered is alphabet, digit or special

character using library functions.

4. Write a program which display a number between 10 to 100 randomly.

5. Write a program which accept a letter and display it in uppercase letter.


Structures

A structure is a collection of variable which can be same or different types. The structure name becomes a user-defined data type and may be used the same way as other built-in data types, such as int, double, char.

Defining a structureWhen dealing with the students in a school, many variables of different types are needed. for example.struct STUDENT{ int rollno, age; char name[80]; float marks;};STUDENT is called the structure tag, and is your brand new data type, like int, double or char.

rollno, name, age, and marks are structure members.


Alternate method of declaring variables of type struct:struct STUDENT{ int rollno, age; char name[80]; float marks;} s1, s3;

Accessing of data membersThe accessing of data members is done by using the following format:structure variable.member namefor examplecin>>s1.rollno>>s1.age>>s1.name>>s1.marks;

Initialization of structure variableInitialization is done at the time of declaration of a variable. For exampleSTUDENT s2 = {100,17,”Aniket”,92};


Structure variable in assignment statements3=s2;

The statement assigns the value of each member of s2 to the corresponding member of s3. Note that one structure variable can be assigned to another only when they are of the same structure type, otherwise complier will give an error.

Nested structure (Structure within structure)It is possible to use a structure to define another structure. This is called nesting of structure. Consider the following programstruct DAY{ int month, date, year;};

struct STUDENT{ int rollno, age; char name[80]; day date_of_birth; float marks;};


Programs- structures

1. Declare a structure to represent a complex number (a number having a real

part and imaginary part). Write C++ functions to add, subtract, multiply and

divide two complex numbers.

2. An array stores details of 25 students (rollno, name, marks in three subject).

Write a program to create such an array and print out a list of students who

have failed in more than one subject.


typedefIt is used to define new data type for an existing data type. It provides and alternative name for standard data type. It is used for self documenting the code by allowing descriptive name for the standard data type.

The general format is:typedef existing datatype new datatype

for example:typedef float real;Now, in a program one can use datatype real instead of float.Therefore, the following statement is valid: real amount;

Enumerated data typeThe enum specifier defines the set of names which are stored internally as integer constant. The first name was given the integer value 0, the second value 1 and so on.for example:enum months{jan, feb, mar, apr, may} ;It has the following features:It is user defined.It works if you know in advance a finite list of values that a data type can take.The list cannot be input by the user or output on the screen.


#define preprocessor directiveThe #define preprocessor allows to define symbolic names and constants e.g. #define pi 3.14159This statement will translate every occurrence of PI in the program to 3.14159

Storage Class

A storage class defines the scope (visibility) and life time of variables and/or functions within a C++ Program. These specifiers precede the type that they modify. There are following storage classes which can be used 1. auto2. register3. static4. extern


The auto Storage ClassThe auto storage class is the default storage class for all local variables.

{ int mount; auto int month; }

The example above defines two variables with the same storage class, auto can only be used within functions, i.e. local variables.

The register Storage Class

The register storage class is used to define local variables that should be stored in a register instead of RAM. { register int miles; }The register should only be used for variables that require quick access such as counters.

The static Storage Classinstructs the compiler to keep a local variable in existence during the lifetime of the program instead of creating and destroying it each time it comes into and goes out of scope. Therefore, making local variables static allows them to maintain their values between function calls.static int a=10;

extern Storage Classis used to give a reference of a global variable that is visible to ALL the program files. When you use 'extern' the variable cannot be initialized as all it does is point the variable name at a storage location that has been previously defined.The extern modifier is most commonly used when there are two or more files sharing the same global variables or functions as explained below.


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