PDA Glossary

A string with no characters and length 0, represented by two quotation marks.

A part of a string specified by a range of indices.

An integer value used to select an item in a sequence, such as a character in a string. In Python indices start from 0.

One of the values in a sequence.

An ordered collection of values where each value is identified by an integer index.

Something a variable can refer to. For now, you can use “object” and “value” interchangeably.

A general process for solving a category of problems.

A loop in which the terminating condition is never satisfied.

Repeated execution of a set of statements using either a recursive function call or a loop.

An update that decreases the value of a variable.

An update that increases the value of a variable (often by one).

An assignment that gives an initial value to a variable that will be updated.

An assignment where the new value of the variable depends on the old.

Assigning a new value to a variable that already exists.

A programming pattern that uses a conditional statement to check for and handle circumstances that might cause an error.

Code that is used during program development but is not part of the final version.

A program development plan intended to avoid debugging by adding and testing only a small amount of code at a time.

Part of a program that can never run, often because it appears after a return statement.

A variable used to store an intermediate value in a complex calculation.

A recursion that doesn’t have a base case, or never reaches it. Eventually, an infinite recursion causes a runtime error.

A conditional branch in a recursive function that does not make a recursive call.

The process of calling the function that is currently executing.

A statement that causes a function to end immediately and return to the caller.

A conditional statement that appears in one of the branches of another conditional statement.

A conditional statement with a series of alternative branches.

One of the alternative sequences of statements in a conditional statement.

A statement that consists of a header and a body. The header ends with a colon (:). The body is indented relative to the header.

The boolean expression in a conditional statement that determines which branch runs.

A statement that controls the flow of execution depending on some condition.

One of the operators that combines boolean expressions: and, or, and not.

One of the operators that compares its operands: ==, !=, >, <, >=, and <=.

An expression whose value is either True or False.

An operator, denoted with a percent sign (%), that works on integers and returns the remainder when one number is divided by another.

An operator, denoted //, that divides two numbers and rounds down (toward negative infinity) to an integer.