In C++, the if
and else
statements are used for conditional execution of code. They allow us to execute certain blocks of code based on whether a specified condition is true or false. The if
statement is used to execute code when a given condition is true, and the else
statement is used to execute code when the condition is false.
Here's the basic syntax of an if
-else
statement in C++:
cppif (condition) {
// Code to be executed if the condition is true
} else {
// Code to be executed if the condition is false
}
Here's a simple example to illustrate the usage of the if
-else
statement:
cpp#include <iostream>
int main() {
int number;
std::cout << "Enter a number: ";
std::cin >> number;
if (number > 0) {
std::cout << "The number is positive." << std::endl;
} else {
std::cout << "The number is non-positive." << std::endl;
}
return 0;
}
In this example, the program prompts the user to enter a number. Then, it uses an if
-else
statement to check whether the entered number is greater than zero. If the condition (number > 0)
is true, the code within the if
block is executed, and it prints "The number is positive." If the condition is false, the code within the else
block is executed, and it prints "The number is non-positive."
We can also have more complex conditions using logical operators like &&
(logical AND) and ||
(logical OR) within the if
statement.
Remember that the else
block is optional. If we only need to execute code when the condition is true, we can use just the if
statement without an else
block.
Let's dive into more details about the if
-else
statement in C++.
Basic if
-else
Structure:
cppif (condition) {
// Code to be executed if the condition is true
} else {
// Code to be executed if the condition is false
}
Multiple if
Statements (if-else if-else chain):
We can have multiple if
statements in an if-else chain to test multiple conditions in sequence. The first true condition's block of code will be executed. If none of the conditions is true, the code in the else
block (if present) will be executed.
cppif (condition1) {
// Code to be executed if condition1 is true
} else if (condition2) {
// Code to be executed if condition2 is true
} else {
// Code to be executed if neither condition1 nor condition2 is true
}
Nested if
-else
Statements:
We can also nest if
-else
statements inside each other to handle more complex conditions.
cppif (outerCondition) {
// Code for outer condition
if (innerCondition) {
// Code for inner condition
} else {
// Code if inner condition is false
}
} else {
// Code if outer condition is false
}
Ternary Operator (Conditional Operator):
C++ also supports a shorthand form of the if
-else
statement called the ternary operator. It's used to assign a value based on a condition.
cppvariable = (condition) ? value_if_true : value_if_false;
Example of Ternary Operator:
cpp#include <iostream>
int main() {
int number;
std::cout << "Enter a number: ";
std::cin >> number;
std::string result = (number > 0) ? "Positive" : "Non-positive";
std::cout << "The number is " << result << std::endl;
return 0;
}
In this example, the ternary operator is used to assign the appropriate label ("Positive" or "Non-positive") to the result
variable based on the condition number > 0
.
Remember that clear and readable code is important. While nested if
-else
statements and the ternary operator can be powerful tools, excessive nesting or overly complex conditions can make our code harder to understand.
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