C++ has the following conditional statements:

• Use if to specify a block of code to be executed, if a specified condition is true

• Use else to specify a block of code to be executed, if the same condition is false

• Use else if to specify a new condition to test, if the first condition is false

• Use switch to specify many alternative blocks of code to be executed

The if Statement

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

Syntax

if (condition) { // block of code to be executed if the condition is true }

Example

#include <iostream>
using namespace std;

int main() {
  int x = 20;
  int y = 18;
  if (x > y) {
    cout << "x is greater than y";
  }  
  return 0;
} //result  x is greater than y

The else Statement

Use the else statement to specify a block of code to be executed if the condition is false.

Syntax

if (condition) { // block of code to be executed if the condition is true } else { // block of code to be executed if the condition is false }

Example

#include <iostream>
using namespace std;

int main() {
  int time = 20;
  if (time < 18) {
    cout << "Good day.";
  } else {
    cout << "Good evening.";
  }
  return 0;
} //result Good evening.

C++ Else If

Use the else if statement to specify a new condition if the first condition is false

Syntax

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 is false and condition2 is false }

Example

int main() {
  int time = 22;
  if (time < 10) {
    cout << "Good morning.";
  } else if (time < 20) {
    cout << "Good day.";
  } else {
    cout << "Good evening.";
  }
  return 0;
} // result Good evening.

C++ Switch

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

Syntax

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

This is how it works:

• The switch expression is evaluated once

• The value of the expression is compared with the values of each case

• If there is a match, the associated block of code is executed

• The break and default keywords are optional and will be described later in this chapter

#include <iostream>
using namespace std;
int main(){
int day=4;
switch (day)
{
case 1: 
cout<<"mmonday";
    break;
    case 2:
    cout<<"tuesday";
    break;
    case 3:
    cout<<"wednesday";
    break;
    case 4:
    cout<<"thersday";
    break;
    case 5:
    cout<<"friday";
    break;
    case 6:
    cout<<"satutrday";
    break;
    case 7:
    cout<<"sundat";


default:
    break;
}

  return 0;
}// result thersday