C Programming Input output Conditional statements and Iterative statements Rohit Khokher.
Decision Making Statements In Programming
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Transcript of Decision Making Statements In Programming
Decision Making Statements
if statement
The if else statement executes one or more commands when a condition is true.
If condition is false then those commands are ignored and are not executed.
if statement#include<iostream.h>#include<conio.h>void main(void){ clrscr();
int a;cout<<"Enter value";cin>>a;if(a>=10){
cout<<“BSCS";}else{
cout<<“MCS";}getch();
}
Operation of if else statement
Nested if statement#include<iostream.h>#include<conio.h>void main(void){ clrscr();
int a, b, c;cout<<"Enter values for A, B and C ";cin>>a>>b>>c;if(a==b){
if(b==c){cout<<"A. B and C are Equal";}else{cout<<"B and C are not Equal";}
}else{cout<<"A and B are not Equal";}getch();
}
OutputEnter values for A, B and C 5 5 8B and C are not Equal
Enter values for A, B and C 5 3 3A and B are not Equal
Enter values for A, B and C 4 4 4A. B and C are Equal
Enter values for A, B and C 8 6 8A and B are not Equal
If StatementIf condition is true
statements
If Ali’s height is greater then 6 feetThen
Ali can become a member of the Basket Ball team
If Statement in C
If (condition)statement ;
If Statement in CIf ( condition ){
statement1 ;statement2 ;
:}
If statement in C
if (age1 > age2)cout<<“Student 1 is older than student 2” ;
Relational Operators< less than<= less than or equal to== equal to>= greater than or equal to> greater than!= not equal to
Relational Operators
a != b;
X = 0;X == 0;
Example#include <iostream.h>main ( ) {
int AmirAge, AmaraAge;AmirAge = 0;AmaraAge = 0;
cout<<“Please enter Amir’s age”;cin >> AmirAge;cout<<“Please enter Amara’s age”;cin >> AmaraAge;
if AmirAge > AmaraAge) {
cout << “\n”<< “Amir’s age is greater then Amara’s age” ;}
}
Flow Chart SymbolsStart or stop
Process
Continuation mark
Decision
Flow line
Flow Chart for if statement
Condition
Process
IF
Then
Entry point for IF block
Exit point for IF block
Note indentation from left to right
ExampleIf the student age is greater than 18
or his height is greater than five feet then put him on the foot balll team
ElsePut him on the chess team
Logical Operators
AND &&OR ||
Logical OperatorsIf a is greater than b
AND c is greater than d
In Cif(a > b && c> d)if(age > 18 || height > 5)
if-elseif (condition){
statement ;--
}else{
statement ;--
}
if-elseCondition
Process 1
IF
Then
Entry point for IF-Else block
Exit point for IF block
Process 2
Else
Note indentation from left to right
Code
if (AmirAge > AmaraAge) { cout<< “Amir is older than Amara” ;}
if (AmirAge < AmaraAge) { cout<< “Amir is younger than Amara” ;}
Example
ExampleCode
if AmirAge > AmaraAge) { cout<< “Amir is older than Amara” ;} else { cout<<“Amir is younger than Amara” ;}
Example Code
if AmirAge > AmaraAge) { cout<< “Amir is older than Amara” ;} else { cout<<“Amir is younger than or of the same age as
Amara” ;}
ExampleIf (AmirAge != AmaraAge) cout << “Amir and Amara’s Ages
are not equal”;
Unary Not operator !
!true = false !false = true
If (!(AmirAge > AmaraAge))
?
Example
if ((interMarks > 45) && (testMarks >= passMarks)){
cout << “ Welcome to Virtual University”;}
Example
If(!((interMarks > 45) && (testMarks >= passMarks)))
?
Nested ifIf (age > 18){
If(height > 5){
:}
}Make a flowchart of this nested if structure…
In Today’s Lecture Decision
If Else
Flowcharts Nested if
Counting words and characters with different technique#include<iostream.h>#include<conio.h>void main(void){
int chcount=0;int wdcount=1;char ch;clrscr();while((ch=getche()) !='\r'){ if(ch==' ')
wdcount++;else
chcount++;}cout<<"\nWords = "<<wdcount;cout<<"\nCharacters = "<<chcount;getch();
}
Outputhello how are youWords = 4Characters = 14
The switch statement The switch statement is similar to the if
else or else if construct but is more flexible.
If decision tree is large, and all the decisions depend on the value of the same variable, then it is better to use switch statement instead of series of if else or else if statements.
The switch statement#include<iostream.h>#include<conio.h>void main(void){ clrscr();
char ch=‘b’;cout<<“Enter character”;cin>>ch;switch(ch){
case ‘b':cout<<“BSCS”<<endl;break;
case ‘m':cout<<“MCS”<<endl;break;
default:cout<<“BSCS and MCS";
}getch();}
The break statement The break keyword causes the entire switch
statement to exit. Control goes to the first statement following the end of the switch statement.
If break statement is not used then the control passes down to the next case statement and the statements that we do not want to execute, starts executing.
If the value of the switch variable doesn’t match any of the case constants then control passes to the end of the switch without doing anything
Defining Label and use of switch, break and goto statements
#include<iostream.h>#include<conio.h>void main(void) // main start{ clrscr();int a, b;char ch;cout<<"Enter 1st value ";cin>>a;cout<<"Enter 2nd value ";cin>>b;again:cout<<"+, -, x, / ";ch=getche();cout<<endl;
switch(ch){case '+':cout<<a<<" + "<<b<<" = "<<a+b<<endl;break;case '-':cout<<a<<" - "<<b<<" = "<<a-b<<endl;break;case 'x':cout<<a<<" x "<<b<<" = "<<a*b<<endl;break;case '/':cout<<a<<" / "<<b<<" = "<<a/b<<endl;break;default:cout<<"Wrong Choice\n";goto again;
}getch();} // main end
Example
EXAMPLEUsing multiple cases in switch
statement
#include<iostream.h>#include<conio.h>void main(void){ clrscr();int a, b;char ch;cout<<"Enter 1st value ";cin>>a;cout<<"Enter 2nd value ";cin>>b;cout<<"1. Add\n";cout<<"2. Subtract\n";cout<<"3. Multiply\n";cout<<"4. Divide\n";again:cout<<"Enter your choice (1-4) ";ch=getche();cout<<endl;
switch(ch) {
case '1':case 'A':case 'a':
cout<<a<<" + "<<b<<" = "<<a+b<<endl;break;
case '2':case 'S':case 's':
cout<<a<<" - "<<b<<" = "<<a-b<<endl;break;
case '3':case 'M':case 'm':
cout<<a<<" x "<<b<<" = "<<a*b<<endl;break;
case '4':case 'D':case 'd':
cout<<a<<" / "<<b<<" = "<<a/b<<endl;break;
default:cout<<"Wrong Choice\n";goto again;
}getch();}
The Conditional Operator There is a compressed way of expressing the if else statement and
is called the conditional operator.#include<iostream.h>#include<conio.h>void main(void)
{ clrscr();int a, b;cout<<"Enter 1st value ";cin>>a;cout<<"Enter 2nd value ";cin>>b;(a > b) ? cout<<"1st value is greater" : cout<<"2nd value is greater";getch();
}