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Conditionals & Logic

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if Statement

An if statement is used to test an expression for truth.

  • If the condition evaluates to true, then the code within the block is executed; otherwise, it will be skipped.
if (a == 10) {
  // Code goes here
}

else Clause

An else clause can be added to an if statement.

  • If the condition evaluates to true, code in the if part is executed.
  • If the condition evaluates to false, code in the else part is executed.
if (year == 1991) {
  // This runs if it is true
}
else {
  // This runs if it is false
}

Relational Operators

Relational operators are used to compare two values and return true or false depending on the comparison:

  • == equal to

  • != not equal to

  • > greater than

  • < less than

  • >= greater than or equal to

  • <= less than or equal to

if (a > 10) {
   // ☝️ means greater than
}

else if Statement

One or more else if statements can be added in between the if and else to provide additional condition(s) to check.

if (apple > 8) {
  // Some code here
}
else if (apple > 6) {
  // Some code here
}
else {
  // Some code here
}

switch Statement

A switch statement provides a means of checking an expression against various cases. If there is a match, the code within starts to execute. The break keyword can be used to terminate a case.

default is executed when no case matches.

switch (grade) {
  case 9:
    std::cout << "Freshman\n";
    break;
  case 10:
    std::cout << "Sophomore\n";
    break;
  case 11:
    std::cout << "Junior\n";
    break;
  case 12:
    std::cout << "Senior\n";
    break;
  default:
    std::cout << "Invalid\n";
    break;
}

Logical Operators

Logical operators can be used to combine two different conditions.

  • && requires both to be true (and)
  • || requires either to be true (or)
  • ! negates the result (not)
if (coffee > 0 && donut > 1) {
  // Code runs if both are true
}


if (coffee > 0 || donut > 1) {
  // Code runs if either is true
}


if (!tired) {
  // Code runs if tired is false
}

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