06. Conditional Statements

NOTE

Control flow = Conditional Statements

if

---

Use the if statement to specify a block of C++ code to be executed if a condition is true.

if(condition){
	// Block gets executed if the condition is true
	// Some logic here
}

#include<iostream>
using namespace std;
 
int main(){
 
	int phone = 15; // 15k
	int money;
	
	cout << "Enter the money you have" << endl;
	//Read money 
	cin >> money;
	
	if(money>=phone){
		cout << "Lets buy the phone" << endl;
		}
	else{
		cout << "Lets wait for the sale" << endl;	
		}
	
	cout << "Thanks for shopping" << endl; // Always get executed 
	return 0;
}

if-else

---

else statement

---

The else statement is used along with the if block. Use the else statement to specify a block of code to be executed if the condition us false.

if(condition){
	// Block gets executed if the condition is true
	// Some logic here
}
else{
	// Some code, execute when the condition is false 
}

Multiple If’s

---

#include<iostream>
#include<cstring>
using namespace std;
 
int main(){
 
	int phone = 15; // 15k
	string weather;
	int money;
	
	cin >> money >> weather;
	// cout << "Enter the money you have" << endl;
	// Multiple If Blocks
	// Shopping 
	if(money>phone){
		cout << "Lets buy the phone" << endl; // condition 1
		}
	// Picnic
	if(weather==pleasant){
		cout << "Lets go for a picnic" << endl; // condition 2
		}
	else{
		cout << "Lets play indoor games" << endl;// else block only depends upon condition 2
		}
	return 0;
}

else-if

---

Use the else if statement to specify a new condition if the previous block condition false.

if (condition1){
	// Block of code to be executed if condition1 is true
}
else if (condition2){
	// Block of code to be executed if the condition1 is false  and condition2 is true
}
else {
// Block of code to be executed if the condition1 and condition2 both are false
}

Ternary Operator [?:]

---

• It consist of three operands, hence the name is ternary operator.
• It is often used to replace simple if else statements.

// Syntax
variable = (condition) ? expressionTrue : expressionFalse 

#include<iostream>
#include<cstring>
using namespace std;
 
int main(){
 
	string weather;
	int temp;
	cin >> temp;
	
	/* Replaceable code
	
	if(temp>30){
		weather = "hot";
		}
	else{
		weather  = "Pleasant";
		}
		*/
	
	// Ternary operator 
	weather = temp > 30 ? "Hot" : "Pleasant";
	cout << weather << endl;
	return 0;
}

Switch Case

---

Use the switch statement to select one of many code blocks to be executed.

switch(expression){
	case x:
		// code block 
		break;
	case y:
		// code block
		break;
	default:
		// code block
}

• The switch expression is evaluated once.
• The value of the expression is compared with the values of each case.
• No complex conditions for a case.
• If there is a match, the associated block of code is executed.