C++ if/else Statements

• Conditional operators are used in programming to make decisions based on conditions.
• The types of conditional operators include:
  • if/else
  • switch

Conditional Statements in C++

• The if/else statement executes a block of code if a condition is true, otherwise it executes another block.
• If the condition in an if statement is true, the "Hello" message prints; otherwise, the "Hi" message prints.
• The conditional if/else statement can also check inner conditions.
• When the first condition is true, the second block will not be considered.
• The if-else-if conditions are used to perform different actions based on a particular grade.
• endl or \n prints a new line in the output.
• Before return 0;, write system("pause"); if the screen does not pause after running the code in Visual Studio.

Important Note

• Do not use a semi-colon ; at the end of a condition.
• The else block only executes when all other conditions fail.

Character Assignment

• Assign a character value using single quotes: char variable = 'c';
• The following code is used to check if the character is a lowercase alphabet: if (var >= 'a' && var <= 'z')
• Numbers are called ASCII.

If Statement

• The single if statement executes code if a condition is true and is also known as a one-way selection statement.
• To execute only one statement in if or else, curly brackets {} can be skipped. If multiple statements are required, enclose them within curly brackets.

If-else Statement

• The if-else statement executes code if a condition is true or false and is called a two-way selection statement.

Nested If Statement

• A nested if statement is an if statement inside another if statement.

If-else-if Statement

• The if-else-if statement is used when multiple conditions need to be checked.

Switch Statement

• The Syntax for the switch statement is as follows:

switch (n)
{
case constant1:
  // code to be executed if n is equal to constant1;
  break;
case constant2:
  // code to be executed if n is equal to constant2;
  break;
default:
  // code to be executed if n doesn't match any constant
}

Loops

• Loops are used to repeat a specific block of code until an end condition is met.
• There are three types of loops:
  • for loop
  • while loop
  • do...while loop

For Loop

• The syntax for loop is as follows:

for(initialization Statement(counter); testExpression; updateStatement)
{
  // code
}

• The steps for how for loop works are:
  • The initialization statement is executed only once at the beginning.
  • Then, the test expression is evaluated.
  • If the test expression is false, the loop is terminated.
  • If the test expression is true, codes inside the body of the for loop is executed and the update expression is updated.
  • The test expression is evaluated again until the test expression is false.

While Loop

• The syntax for loop is as follows:

while (testExpression)
{
  // codes
}

• The steps for how while loop works are:
  • The while loop evaluates the test expression.
  • If the test expression is true, codes inside the body of the while loop is evaluated.
  • Then, the test expression is evaluated again and continues until the test expression is false.
  • When the test expression is false, the while loop is terminated.

Do...While Loop

• The do...while loop is a variant of the while loop with one key difference: the body of the do...while loop is executed once before the test expression is checked.
• The syntax for loop is as follows:

do {
  // codes;
}
while (testExpression);

• The steps for how while loop works are:
  • The codes inside the body of the loop is executed at least once.
  • The test expression is checked.
  • If the test expression is true, the body of loop is executed, continuing until the test expression becomes false.
  • When the test expression is false, the do...while loop is terminated.