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A Simple Program:
“PrinƟng a Line of Text”
o Document programs
o Improve program readability
o Ignored by compiler
o Single-line comment
- Begins with //
- Multiple-lines comment
- Begins with /* and ends with */
- Preprocessor directives
o Processed by preprocessor before
compiling
o Begin with
o Preprocessor directives can be used in:
Defining used libraries
#include
Defining macro with
parameters
#define sum(a,b) (a+b)
Defining macro constant
#define A 20
- Standard output stream object
- std::cout
- “Connected” to screen
- <<
- Stream insertion operator
- Value to right (right operand) inserted into output stream
- Namespace
- std:: specifies using name that belongs to “namespace” std
- std:: removed through use of using statements using namespace std
- Escape characters
- \
- Indicates “special” character output
- Input stream object
- >> (stream extraction operator)
- Used with std::cin
- Waits for user to input value, then press Enter (Return) key
- Stores value in variable to right of operator
- Converts value to variable data type
- = (assignment operator)
- Assigns value to variable
- Binary operator (two operands)
- Example: sum = variable1 + variable2;
“Memory Concepts”
- Variable names
- Correspond to actual locations in computer's memory
- Every variable has name, type, size and value
- When new value placed into variable, overwrites previous value in memory
- Reading variables from memory nondestructive
“Using statement”
- Eliminate use of std:: prefix
- Write cout instead of std::cout Without the use of using statement: std::cin>>x; With the use of using statement: using namespace std; cin>>x; cin, cout, endl can be used alone EXAMPLE 1: Write a program to prompt the user to enter his name initial, age, and height and display them on the screen Inputs: name iniƟal, age, height Outputs: name iniƟal, age, height Formula: None Constants: None #include using namespace std; int main() { char name_I; int age; float height; cout<<“Please enter your name iniƟal, age and height \n”; cin>>name_I>>age>>height; cout<<“name is”< #include using namespace std; int main() { const int one_tree_space = 4; int length, width, area, no_of_trees; cout<<“Enter the length of the land \n”; cin>>length; cout<<“Enter the width of the land \n”; cin>>width; area = Length*width; no_of_trees= area/one_tree_space; cout<<“The available number of trees = “< using namespace std; int main() { const float PI = 3.141593; float radius, area, circum; cout<<“Enter radius of the circle \n”; cin>>radius; area = PI * radius * radius; circum = 2 * PI * radius; cout<<“The area of the circle = “<
EXAMPLE 4:
Write a program to define two integer variables containing 3 and 5, then calculate their sum and their product and display the result. You must use comments. Inputs: None Outputs: sum, product Formula: sum = first + second Product = first * second Constants: first=3, second = // This program calculates the sum and product of 3 and 5 #include using namespace std; int main() { int first, second, sum, product; //declaring variables first = 3; second = 5; sum = first + second ; //calculaƟng sum product = first * second; //calculaƟng product cout<<“The sum is “<< sum<<“ \n”; cout<<“The product is “<< product<<“ \n”; return 0 ; }
#include using namespace std; int main() { int No1, No2, Temp; cout<<"Enter two numbers\n"; cin>>No1>>No2; cout<<"Before Swapping\n"; cout<<"1st Number is:"< “ArithmeƟc expressions”
There are many operators for manipulaƟng numeric values
and performing arithmeƟc operaƟons
We have
Integer arithmeƟc operaƟons
float arithmeƟc operaƟons
Integer
results
float
results
2. Arithmetic Expression
An expression is a valid arrangement of variables, constants, and operators. C++ applies the operators in arithmetic expressions in a precise sequence determined by the following rules of operator precedence, which are generally the same as those in algebra:
Operators Precedence
( )
3. Shortcut assignment
4. Mathematical Library Functions
The cmath library provides a lot of useful predefined math
functions.
Before you use them, remember to include the math
library in your code:
#include
R1 = (-b + sqrt(pow(b,2) – 4 * a * c)) / (2 * a);
R2 = (-b - sqrt(pow(b,2) – 4 * a * c)) / (2 * a);
R1=
a
b b ac
a
b b ac
2
R2=
Inputs: a, b, c Outputs: R1, R Formula: d = pow(b,2) – 4 * a * c; R1 = (-b + sqrt(d)) / (2 * a); R2 = (-b - sqrt(d)) / (2 * a); Constants: None
#include #include int main() { using namespace std; double a,b,c,d,x1,x2; cout<<"Enter the equaƟon coefficients:"; cin>>a>>b>>c; d=(bb-4ac); if (d<0) cout<<"The two roots are imaginary"; else { d=sqrt(d); x1=(-b+d)/(2a); x2=(-b-d)/(2*a); cout<<"The two roots are"<<"\n"; cout< Making Decisions (selecƟon) - II SWITCH Statement
⮚ Used to select one of several alternatives
⮚ BASED on the value of a single variable.
⮚ This variable may be an int or a char but NOT a float
or double.
Switch (variable) { case constant_1: acƟon_1; break; case constant_2: acƟon_2; break; case constant_3: acƟon_3; break; default: acƟon_4; }
SYNTAX
break is very important. WHY?
Write a C++ program that accept a leƩer A, B, or C and print
the entered leƩer. You must use SWITCH
