C++ Nested if
C++'s nested if statements enable more complex decision-making when a section of code needs to execute only after a set of conditions is met. The nested if control statement refers to the if condition within the if condition. C++ compiler checks nested if control statement when its parent if condition returns true; the program is executed according to the nested if condition.
Syntax:
It has the following syntax:
if (condition1) {
if (condition2) {
// Code executes if both condition1 and condition2 are true
}
}
Algorithm:
- Start.
- Declare an integer variable num.
- Prompt the user to enter a number.
- Read and store the value in num.
- Check if num is greater than 0:
- If true, print "The number is positive."
- Then, check if num is even (num % 2 == 0):
- If true, print "The number is even."
- Then, check if num is greater than 10:
- If true, print "The number is greater than 10."
- End the program
Pseudo code:
Begin
Declare num as Integer
Print "Enter a number: "
Input num
If num > 0 THEN
Print "The number is positive."
If num MOD 2 == 0 then
Print "The number is even."
If num > 10 then
Print "The number is greater than 10."
Endif
Endif
Endif
End
Key Features of Nested If Statement:
Several key features of Nested if Statement in C++ are as follows:
- Numerous Condition Checking: This feature makes it possible to verify several conditions in a hierarchical manner.
- The outside if determines the inner if. The inner if statement executes only in the event that the outer if condition is true.
- It supports both else and otherwise if we can use nested if blocks to enclose else or else if statements in order to provide alternative results.
- Enhances Decision-Making: It is helpful when existing circumstances depend on past ones.
- A Variety of Levels Are Possible: It allows for multiple nesting levels, while excessive nesting could make the text harder to read.
- Keeps Code Flow Control: It helps with the organization of intricate conditional logic.
Key Points:
- The inner if is only executed if the outer if condition is true.
- It makes handling complex decision-making scenarios easier.
- Maintaining appropriate indentation and structure is crucial since overuse can make text more difficult to read.
Example 1: Basic Nested if statement Block:
In these codes, it checks whether the number is even and positive or not.
#include <iostream>
using namespace std;
int main() {
int num = 10;
if (num > 0) { // Outer if: checks if the number is positive
if (num % 2 == 0) { // Inner if: checks if the number is even
cout << "The number is positive and even." << endl;
}
}
return 0;
}
Output:
The number is positive and even.
Example 2: Nested if containing Else:
In these codes, it checks whether the number is positive, negative even or odd:
#include <iostream>
using namespace std;
int main() {
int num;
cout << "Enter a number: ";
cin >> num;
if (num > 0) {
cout << "The number is positive." << endl;
if (num % 2 == 0) {
cout << "It is even." << endl;
} else {
cout << "It is odd." << endl;
}
} else if (num < 0) {
cout << "The number is negative." << endl;
} else {
cout << "The number is zero." << endl;
}
return 0;
}
Output:
Enter a number: 11 The number is positive. It is odd.
Example 3: Multiple levels of Nested if:
In these, we determine the criteria for a person who is eligible to vote based on age and citizenship:
#include <iostream>
using namespace std;
int main() {
int age;
char citizenship;
cout << "Enter your age: ";
cin >> age;
cout << "Are you a citizen? (y/n): ";
cin >> citizenship;
if (age >= 18) { // First condition
if (citizenship == 'y' || citizenship == 'Y') { // Second condition
cout << "You are eligible to vote." << endl;
} else {
cout << "You must be a citizen to vote." << endl;
}
} else {
cout << "You must be at least 18 years old to vote." << endl;
}
return 0;
}
Output:
Enter your age: 20 Are you a citizen? (y/n): y You are eligible to vote.
Conclusion:
In conclusion, the flexible control structure of C++'s nested if statements allow programmers to manage complex decision-making by hierarchically checking a variety of scenarios. The inner if only executes when the outer if condition is satisfied to guarantee logical flow and well-organized decision-making. When more than one level of verification is required, such as when verifying user inputs based on multiple criteria or figuring out a voter's age and citizenship, this functionality is useful. Appropriate indentation and structure are essential, while layering increases code flexibility, doing so too much can make the code less readable. When it comes to writing logical and efficient C++ applications, nested if statements are crucial.