synatx and semnatics

• Like any human language, all programming languages have syntax and semantics.
• Syntax refers to the rules of the programming language.
• semantics is related to the meaning of elements of a program and what they do.
• If a program violates any of the syntax rules of a language, the compiler or the interpreter produces an error message called syntax error.
• A program can have no syntax error and get executed properly but can still behave in a way different from what it is intended to This kind of error is known as logic error
• logic error is associated with the semantics of a language.
• Since compilers or interpreters do not catch logic errors, they are far more difficult to identify and fix than syntax errors.
• Python is one of the popular high-level programming languages in use today.
• python is considered a much easier language to learn and one of the main reasons why it is a widely chosen language for teaching programming to those who are new to programming.
• Python has a free IDLE.
• IDLE stands for Integrated Development and Learning Environment.
• To write Python codes, the interactive interpreter or the text editor of the IDLE can be used.
• The interactive interpreter is used to write one line of Python code at a time and is less convenient to write and execute a large number of codes
• in text editor any number of codes can be written and get executed with a single command.
• The Interactive Interpreter contains a Python shell
• python shell is a textual user interface used to work with the Python language.
• The Interactive Interpreter is displayed when the IDLE is opened.
• The >>> is where codes are written and is called the prompt
• To display something on the screen, the print() function is used in Python
• IDLE uses different types of colors for the differentelements of a Python code to make them easily distinguishable.
• -> outputs - blue -> functions - purple -> strings - green
• string is a sequence of characters placed under quotation marks
• The code that is kept in such files is known as a script.
• A file that keeps Python scripts is saved with the .py extension and is called a script file
• The prompt appears only when code is written in the interactive interpreter, not inthe text editor.
• While only one line of code is written and executed in the interactive interpreter, as many lines of code as required can be written in the text editor.
• Before the script is run the script has to be saved with the .py extension by selecting the “save” option from the “file” menu in the text editor.
• To execute the script, the “Run Module” option from the “Run” Menu should be selected.
• After the script is executed, the output is displayed in the IDLE shell/interactive interpreter in a format
• Though there are four statements in the script, only one output is shown in the IDLE shell. This is because it is only the last statement that produces an output
• The * is multiplication operator in Python and ** is exponentiation operator
• the interpreter did not generate any error and simply displayed the incorrect output. This is a logic error
• Variables are computer memory locations.
• variables are the means to store data in computer memory.
• a variable is created along with its value.
• Values are assigned to variables using the assignment (=) operator, which has two operands.
• The operand to the left of the operator is always a variable while the operand to the right of the operator is either a literal value or any other type of expression.
• a variable can be assigned to another value than the one it was previously assigned to.
• The name that is given to variables is called an identifier.
• Identifiers are a string of one or more characters and have to conform to some rules in Python to be considered valid.