C/C++ if else statement with Examples
Decision Making in C/C++ helps to write decision driven statements and execute a particular set of code based on certain conditions.
The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the C/C++ else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
Syntax:
if (condition) { // Executes this block if // condition is true } else { // Executes this block if // condition is false }
Working of if-else statements
- Control falls into the if block.
- The flow jumps to Condition.
- Condition is tested.
- If Condition yields true, goto Step 4.
- If Condition yields false, goto Step 5.
- The if-block or the body inside the if is executed.
- The else block or the body inside the else is executed.
- Flow exits the if-else block.
Example 1:
C
// C program to illustrate If statement #include <stdio.h> int main() { int i = 20; // Check if i is 10 if (i == 10) printf ( "i is 10" ); // Since is not 10 // Then execute the else statement else printf ( "i is 20" ); printf ( "Outside if-else block" ); return 0; } |
C++
// C++ program to illustrate if-else statement #include <iostream> using namespace std; int main() { int i = 20; // Check if i is 10 if (i == 10) cout << "i is 10" ; // Since is not 10 // Then execute the else statement else cout << "i is 20\n" ; cout << "Outside if-else block" ; return 0; } |
Output:
i is 20 Outside if-else block
Dry-Running Example 1:
1. Program starts. 2. i is initialized to 20. 3. if-condition is checked. i == 10, yields false. 4. flow enters the else block. 4.a) "i is 20" is printed 5. "Outside if-else block" is printed.
Example 2:
C
// C program to illustrate If statement #include <stdio.h> int main() { int i = 25; if (i > 15) printf ( "i is greater than 15" ); else printf ( "i is smaller than 15" ); return 0; } |
C++
// C++ program to illustrate if-else statement #include <iostream> using namespace std; int main() { int i = 25; if (i > 15) cout << "i is greater than 15" ; else cout << "i is smaller than 15" ; return 0; } |
Output:
i is greater than 15
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