assignment statement for computer

• Assignment Statement

An Assignment statement is a statement that is used to set a value to the variable name in a program .

Assignment statement allows a variable to hold different types of values during its program lifespan. Another way of understanding an assignment statement is, it stores a value in the memory location which is denoted by a variable name.

The symbol used in an assignment statement is called as an operator . The symbol is ‘=’ .

Note: The Assignment Operator should never be used for Equality purpose which is double equal sign ‘==’.

The Basic Syntax of Assignment Statement in a programming language is :

variable = expression ;

variable = variable name

expression = it could be either a direct value or a math expression/formula or a function call

Few programming languages such as Java, C, C++ require data type to be specified for the variable, so that it is easy to allocate memory space and store those values during program execution.

data_type variable_name = value ;

In the above-given examples, Variable ‘a’ is assigned a value in the same statement as per its defined data type. A data type is only declared for Variable ‘b’. In the 3 rd line of code, Variable ‘a’ is reassigned the value 25. The 4 th line of code assigns the value for Variable ‘b’.

Assignment Statement Forms

This is one of the most common forms of Assignment Statements. Here the Variable name is defined, initialized, and assigned a value in the same statement. This form is generally used when we want to use the Variable quite a few times and we do not want to change its value very frequently.

Tuple Assignment

Generally, we use this form when we want to define and assign values for more than 1 variable at the same time. This saves time and is an easy method. Note that here every individual variable has a different value assigned to it.

(Code In Python)

Sequence Assignment

(Code in Python)

Multiple-target Assignment or Chain Assignment

In this format, a single value is assigned to two or more variables.

Augmented Assignment

In this format, we use the combination of mathematical expressions and values for the Variable. Other augmented Assignment forms are: &=, -=, **=, etc.

Browse more Topics Under Data Types, Variables and Constants

• Concept of Data types
• Built-in Data Types
• Constants in Programing Language 
• Access Modifier
• Variables of Built-in-Datatypes
• Declaration/Initialization of Variables
• Type Modifier

Few Rules for Assignment Statement

Few Rules to be followed while writing the Assignment Statements are:

• Variable names must begin with a letter, underscore, non-number character. Each language has its own conventions.
• The Data type defined and the variable value must match.
• A variable name once defined can only be used once in the program. You cannot define it again to store other types of value.
• If you assign a new value to an existing variable, it will overwrite the previous value and assign the new value.

FAQs on Assignment Statement

Q1. Which of the following shows the syntax of an  assignment statement ?

• variablename = expression ;
• expression = variable ;
• datatype = variablename ;
• expression = datatype variable ;

Answer – Option A.

Q2. What is an expression ?

• Same as statement
• List of statements that make up a program
• Combination of literals, operators, variables, math formulas used to calculate a value
• Numbers expressed in digits

Answer – Option C.

Q3. What are the two steps that take place when an  assignment statement  is executed?

• Evaluate the expression, store the value in the variable
• Reserve memory, fill it with value
• Evaluate variable, store the result
• Store the value in the variable, evaluate the expression.

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Kenneth Leroy Busbee

An assignment statement sets and/or re-sets the value stored in the storage location(s) denoted by a variable name; in other words, it copies a value into the variable. [1]

The assignment operator allows us to change the value of a modifiable data object (for beginning programmers this typically means a variable). It is associated with the concept of moving a value into the storage location (again usually a variable). Within most programming languages the symbol used for assignment is the equal symbol. But bite your tongue, when you see the = symbol you need to start thinking: assignment. The assignment operator has two operands. The one to the left of the operator is usually an identifier name for a variable. The one to the right of the operator is a value.

Simple Assignment

The value 21 is moved to the memory location for the variable named: age. Another way to say it: age is assigned the value 21.

Assignment with an Expression

The item to the right of the assignment operator is an expression. The expression will be evaluated and the answer is 14. The value 14 would be assigned to the variable named: total_cousins.

Assignment with Identifier Names in the Expression

The expression to the right of the assignment operator contains some identifier names. The program would fetch the values stored in those variables; add them together and get a value of 44; then assign the 44 to the total_students variable.

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• Wikipedia: Assignment (computer science) ↵

Programming Fundamentals Copyright © 2018 by Kenneth Leroy Busbee is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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2.1: Assignment statements

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An assignment statement creates a new variable and gives it a value:

This example makes three assignments. The first assigns a string to a new variable named message ; the second gives the integer 17 to n ; the third assigns the (approximate) value of \(\pi\) to pi .

A common way to represent variables on paper is to write the name with an arrow pointing to its value. This kind of figure is called a state diagram because it shows what state each of the variables is in (think of it as the variable’s state of mind). Figure \(\PageIndex{1}\) shows the result of the previous example.

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Different Forms of Assignment Statements in Python

• Statement, Indentation and Comment in Python
• Conditional Statements in Python
• Assignment Operators in Python
• Loops and Control Statements (continue, break and pass) in Python
• Different Ways of Using Inline if in Python
• Difference between "__eq__" VS "is" VS "==" in Python
• Augmented Assignment Operators in Python
• Nested-if statement in Python
• How to write memory efficient classes in Python?
• Difference Between List and Tuple in Python
• A += B Assignment Riddle in Python
• Difference between List VS Set VS Tuple in Python
• Assign Function to a Variable in Python
• Python pass Statement
• Python If Else Statements - Conditional Statements
• Data Classes in Python | Set 5 (post-init)
• Assigning multiple variables in one line in Python
• Assignment Operators in Programming
• What is the difference between = (Assignment) and == (Equal to) operators

We use Python assignment statements to assign objects to names. The target of an assignment statement is written on the left side of the equal sign (=), and the object on the right can be an arbitrary expression that computes an object.

There are some important properties of assignment in Python :-

• Assignment creates object references instead of copying the objects.
• Python creates a variable name the first time when they are assigned a value.
• Names must be assigned before being referenced.
• There are some operations that perform assignments implicitly.

Assignment statement forms :-

1. Basic form:

This form is the most common form.

2. Tuple assignment:

When we code a tuple on the left side of the =, Python pairs objects on the right side with targets on the left by position and assigns them from left to right. Therefore, the values of x and y are 50 and 100 respectively.

3. List assignment:

This works in the same way as the tuple assignment.

4. Sequence assignment:

In recent version of Python, tuple and list assignment have been generalized into instances of what we now call sequence assignment – any sequence of names can be assigned to any sequence of values, and Python assigns the items one at a time by position.

5. Extended Sequence unpacking:

It allows us to be more flexible in how we select portions of a sequence to assign.

Here, p is matched with the first character in the string on the right and q with the rest. The starred name (*q) is assigned a list, which collects all items in the sequence not assigned to other names.

This is especially handy for a common coding pattern such as splitting a sequence and accessing its front and rest part.

6. Multiple- target assignment:

In this form, Python assigns a reference to the same object (the object which is rightmost) to all the target on the left.

7. Augmented assignment :

The augmented assignment is a shorthand assignment that combines an expression and an assignment.

There are several other augmented assignment forms:

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Variable Assignment

To "assign" a variable means to symbolically associate a specific piece of information with a name. Any operations that are applied to this "name" (or variable) must hold true for any possible values. The assignment operator is the equals sign which SHOULD NEVER be used for equality, which is the double equals sign.

The '=' symbol is the assignment operator. Warning, while the assignment operator looks like the traditional mathematical equals sign, this is NOT the case. The equals operator is '=='

Design Pattern

To evaluate an assignment statement:

• Evaluate the "right side" of the expression (to the right of the equal sign).
• Once everything is figured out, place the computed value into the variables bucket.

We've already seen many examples of assignment. Assignment means: "storing a value (of a particular type) under a variable name" . Think of each assignment as copying the value of the righthand side of the expression into a "bucket" associated with the left hand side name!

Read this as, the variable called "name" is "assigned" the value computed by the expression to the right of the assignment operator ('=');

Now that you have seen some variables being assigned, tell me what the following code means?

The answer to above questions: the assignment means that lkjasdlfjlskdfjlksjdflkj is a variable (a really badly named one), but a variable none-the-less. jlkajdsf and lkjsdflkjsdf must also be variables. The sum of the two numbers held in jlkajdsf and lkjsdflkjsdf is stored in the variable lkjasdlfjlskdfjlksjdflkj.

Examples of builtin Data and Variables (and Constants)

For more info, use the "help" command: (e.g., help realmin);

Examples of using Data and Variable

Pattern to memorize, assignment pattern.

The assignment pattern creates a new variable, if this is the first time we have seen the "name", or, updates the variable to a new value!

Read the following code in English as: First, compute the value of the thing to the right of the assignment operator (the =). then store the computed value under the given name, destroying anything that was there before.

Or more concisely: assign the variable "name" the value computed by "right_hand_expression"

CS101: Introduction to Computer Science I

Variables and Assignment Statements

Read this chapter, which covers variables and arithmetic operations and order precedence in Java.

9. Assignment Statements

No. The incorrect splittings are highlighted in red:

Assignment Statement

So far, the example programs have been using the value initially put into a variable. Programs can change the value in a variable. An  assignment statement  changes the value that is held in a variable. The program uses an assignment statement.

The assignment statement puts the value 123 into the variable. In other words, while the program is executing there will be a 64 bit section of memory that holds the value 123.

Remember that the word "execute" is often used to mean "run". You speak of "executing a program" or "executing" a line of the program.

Question 10:

Assignment Statement

The assignment statement allows you to store a value in a variable. The right-hand side of the assignment is an expression that calculates the value to be stored. The left-hand side is a variable, indicating where the value is to be stored.

With the addition of the custom types you can now also store values in fields of a record or union, or copy across an entire struct in one go.

Struct Assignment

The assignment statement can be used to assign a value to a struct’s fields, or to copy all fields from an existing struct’s value.

To access a field, you use the dot operator ( . ) between the variable name and the field name. For example, var1.field1 . This accesses field1 within the var1 variable. The value on the left-hand side of the dot needs to be a struct. The identifier on the right-hand side is the name of the field to access.

You can chain multiple field accesses together if you have nested structs. For example, var6.field.name would work if field referred to another struct type that contained a name field.

Union Assignment

The Union is similar to a Record in that you can assign values to a union via its fields or by copying another union value into the variable or array element. The difference with the Union is that it has only a single value, with the different fields giving you different interpretations of that data.

As with structs, you can access individual fields within a union using the dot operator. In this case the left-hand side of the dot needs to be a union value, the right-hand side is the identifier of the field you want to access.

Assignment - Why, When, and How

The role of assignment does not change, but now you can use this to assign entire struct values or assign values to individual fields within your structs and unions. This gives you the ability to work with the whole struct, while also having the tools to access parts of it. You can then move between these two levels of detail as you need. In one place you can store a value in a field of the struct, and in another you can pass the whole struct to a parameter in a function or procedure call.

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4.1 - assignment statement basics.

The fundamental method of modifying the data in a data set is by way of a basic assignment statement. Such a statement always takes the form:

variable = expression;

where the variable is any valid SAS name and the expression is the calculation that is necessary to give the variable its values. The variable must always appear to the left of the equal sign and the expression must always appear to the right of the equal sign. As always, the statement must end with a semicolon (;).

Because assignment statements involve changing the values of variables, in the process of learning about assignment statements we'll get practice with working with both numeric and character variables. We'll also learn how using numeric SAS functions can help to simplify some of our calculations.

Example 4.1 Section  

Throughout this lesson, we'll work on modifying various aspects of the temporary data set grades that are created in the following DATA step:

The data set contains student names ( name ), each of their four exam grades ( e1 , e2 , e3 , e4 ), their project grade ( p1 ), and their final exam grade ( f1 ).

A couple of comments. For the sake of the examples that follow, we'll use the DATALINES statement to read in the data. We could have just as easily used the INFILE statement. Additionally, for the sake of ease, we'll create temporary data sets rather than permanent ones. Finally, after each SAS DATA step, we'll use the PRINT procedure to print all or part of the resulting SAS data set for your perusal.

Example 4.2 Section  

The following SAS program illustrates a very simple assignment statement in which SAS adds up the four exam scores of each student and stores the result in a new numeric variable called examtotal .

Note that, as previously described, the new variable name examtotal appears to the left of the equal sign, while the expression that adds up the four exam scores ( e1 + e2 + e3 + e4 ) appears to the right of the equal sign.

Launch and run    the SAS program. Review the output from the PRINT procedure to convince yourself that the new numeric variable examtotal is indeed the sum of the four exam scores for each student appearing in the data set. Also, note what SAS does when it is asked to calculate something when some of the data are missing. Rather than add up the three exam scores that do exist for John Simon, SAS instead assigns a missing value to his examtotal . If you think about it, that's a good thing! Otherwise, you'd have no way of knowing that his examtotal differed in some fundamental way from that of the other students. The important lesson here is to always be aware of how SAS is going to handle the missing values in your data set when you perform various calculations!

Example 4.3 Section  

In the previous example, the assignment statement created a new variable in the data set by simply using a variable name that didn't already exist in the data set. You need not always use a new variable name. Instead, you could modify the values of a variable that already exists. The following SAS program illustrates how the instructor would modify the variable e2 , say for example, if she wanted to modify the grades of the second exam by adding 8 points to each student's grade:

Note again that the name of the variable being modified ( e2 ) appears to the left of the equal sign, while the arithmetic expression that tells SAS to add 8 to the second exam score ( e2 +8) appears to the right of the equal sign. In general, when a variable name appears on both sides of the equal sign, the original value on the right side is used to evaluate the expression. The result of the expression is then assigned to the variable on the left side of the equal sign.

Launch and run    the SAS program. Review the output from the print procedure to convince yourself that the values of the numeric variable e2 are indeed eight points higher than the values in the original data set.

Compiler Design Assignment Statements

Compiler design: translation of assignment statements.

In the field of computer science, compiler design is a crucial area that deals with the development of software tools known as compilers. These compilers are responsible for translating high-level programming languages into machine-readable code, which can be executed by a computer. One important aspect of compiler design is the translation of assignment statements.

Understanding Assignment Statements

Assignment statements are a fundamental component of programming languages. They allow programmers to assign values to variables, which can then be used in subsequent calculations or operations. For example, consider the following assignment statement in the C programming language:

In this example, the variable “x” is assigned the value of 5. This means that whenever the variable “x” is referenced in the program, its value will be 5.

Translation Process

When it comes to translating assignment statements, compilers follow a specific process to convert the high-level code into machine code. Let’s explore this process in more detail:

Lexical Analysis

The first step in the translation process is lexical analysis. This involves breaking down the source code into a series of tokens, such as keywords, identifiers, operators, and literals. In the case of assignment statements, the compiler identifies the tokens that represent the assignment operator (=), the variable name (x), and the value (5).

Syntax Analysis

Once the tokens have been identified, the compiler moves on to syntax analysis. Here, it checks whether the arrangement of tokens follows the grammar rules of the programming language. In the case of assignment statements, the compiler verifies that the syntax is correct, ensuring that the variable name comes before the assignment operator, followed by the value.

Semantic Analysis

After the syntax has been validated, the compiler performs semantic analysis. This involves checking the meaning and validity of the assignment statement. For example, the compiler checks whether the variable “x” has been declared before it is assigned a value. It also verifies whether the assigned value is compatible with the variable’s data type.

Intermediate Code Generation

Once the assignment statement has been validated, the compiler generates an intermediate representation of the code. This intermediate code is a low-level representation that is closer to the machine code but still human-readable. It serves as a bridge between the high-level code and the final machine code.

Code Optimization

At this stage, the compiler may perform code optimization techniques to improve the efficiency and performance of the generated code. These optimizations can include removing redundant code, simplifying expressions, or rearranging instructions for better execution.

Code Generation

Finally, the compiler generates the actual machine code that can be executed by the computer’s processor. This machine code is a binary representation of the assignment statement, where each instruction is encoded in a specific format that the processor can understand.

Let’s consider a simple example to illustrate the translation of an assignment statement. Suppose we have the following assignment statement in the Python programming language:

Here’s how the translation process would work:

Lexical Analysis:

The compiler identifies the tokens as follows:

• Variable: x
• Assignment operator: =
• Literal: 10
• Operator: +
• Variable: y
• Operator: *

Syntax Analysis:

The compiler verifies that the arrangement of tokens follows the syntax rules of the Python language. In this case, the syntax is correct.

Semantic Analysis:

The compiler checks whether the variable “y” has been declared before it is used in the expression. It also verifies whether the types of the operands are compatible with the operators. Assuming that “y” is declared and has a compatible type, the semantic analysis is successful.

Intermediate Code Generation:

The compiler generates an intermediate representation of the assignment statement, such as:

This intermediate code represents the same computation as the original assignment statement but in a more structured form.

Code Optimization:

If applicable, the compiler may perform code optimization techniques to improve the efficiency of the generated code. For example, it could simplify the expression “10 + temp1” to a constant value if it can determine that “temp1” is always the same.

Code Generation:

Finally, the compiler generates the machine code that corresponds to the intermediate code. This machine code can be executed by the computer’s processor to perform the assignment operation.

In summary, the translation of assignment statements is an essential part of compiler design. It involves breaking down the source code into tokens, validating the syntax and semantics, generating intermediate code, optimizing the code if necessary, and finally generating the machine code. Understanding this process helps programmers and computer scientists appreciate the intricate workings of compilers and their role in converting high-level code into executable instructions.

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At a time when computer companies like IBM were selling multimillion-dollar mainframe computers, Digital Equipment Corp., which was founded and run by Kenneth Olsen, aimed at introducing smaller, powerful machines that could be purchased for a fraction of that cost. Hired from the Massachusetts Institute of Technology campus in 1960 as the company’s second computer engineer, Mr. Bell designed all its early entrants into what was then called the minicomputer market.

The PDP-8, a 12-bit computer introduced in 1965 with an $18,000 price tag, was considered the first successful minicomputer on the market. More important, Digital Equipment Corp.’s minicomputers were sold to scientists, engineers, and other users who interacted directly with the machines in an era when corporate computers were off limits to such users, housed in glass-walled data centers under the watchful eye of specialists.

“All the DEC machines were interactive, and we believed in having people talk directly to computers,” Mr. Bell said in a 1985 interview with Computerworld, an industry publication. In this way, Mr. Bell presaged the coming personal computer revolution.

Under the often autocratic Olsen, the company was an engineering-oriented environment in which product lines drove the business, consensus emerged after loud and often caustic debate, and a matrixlike structure blurred the lines of management. This controlled chaos became a source of tremendous stress for Mr. Bell; he often butted heads with Olsen, who was known for keeping close tabs on the work of his engineers, much to Mr. Bell’s chagrin.

Undone by the tension, Mr. Bell took what became a six-year sabbatical to teach at Carnegie Mellon University in Pittsburgh, but he returned to the company as vice president of engineering in 1972. Reinvigorated and brimming with new ideas, he oversaw the design of an entirely new computer architecture. The VAX 780, a fast, powerful and efficient minicomputer, was a huge success, fueling sales that by the early 1980s had made DEC the world’s second-largest computer maker.

“Gordon Bell was a giant in the computer industry,” said Howard Anderson, founder of the Yankee Group, a technology industry research firm that tracked the market in that era. “I give him as much credit for DEC’s success as Ken Olsen. He believed in the primacy of engineering talent, and he attracted some of the best engineers in the industry to DEC, which became a place of great ferment.”

At DEC, the tension between Olsen and Mr. Bell again became unbearable. Stressed by the pressure to keep turning out winners and by Olsen’s overbearing presence, Mr. Bell became quick to anger (he was known to throw erasers at people in meetings) and left his engineers angry and confused. In March 1983, on a ski trip to Snowmass, Colo., with his wife and several of the company’s top engineers, Mr. Bell suffered a massive heart attack in his ski chalet and might have died if not for the efforts of Bob Puffer, a company vice president, who revived him with CPR.

After months of recuperation, he returned to work but decided it was time to leave for good. Over the protests of several top company executives, he quit in the summer of 1983.

Chester Gordon Bell was born Aug. 19, 1934, in Kirksville, Mo., to Chester Bell, an electrician who owned an appliance store, and Lola (Gordon) Bell, who taught grade school.

He developed a congenital heart problem when he was 7 and spent much of the second grade at home, mostly in bed. He spent his confinement wiring circuits, running chemistry experiments, and cutting out puzzles with a jigsaw. After he recovered, he spent countless hours in his father’s shop learning about electrical repair. By age 12, he was a professional electrician — installing the first home dishwashers, fixing motors and tearing apart mechanical gadgets to rebuild them.

Mr. Bell graduated from the Massachusetts Institute of Technology in 1957 with a master’s degree in electrical engineering. He then earned a Fulbright scholarship to the University of New South Wales in Australia, where he developed and taught the university’s first graduate course in computer design. While there, he met Gwen Druyor, another Fulbright scholar, whom he married in 1979 and with whom he would found the Computer History Museum in Boston in 1996. They divorced in 2002.

Although he returned to MIT and worked toward a doctorate, Mr. Bell abandoned that effort to join Digital Equipment Corp. He had no interest in research, believing that it was an engineer’s job to build things.

After he left the company, Mr. Bell was a founder of both Encore Computer and Ardent Computer. In 1986, he delved into the world of public policy when he joined the National Science Foundation and led the supercomputer networking effort that resulted in an early iteration of the internet called the National Research and Education Network. In 1987, he sponsored the ACM Gordon Bell Prize for work in parallel computing.

He eventually moved to California, where he became a Silicon Valley angel investor and, in 1991, an adviser to Microsoft, which was opening its first research lab in Redmond, Wash. Mr. Bell joined the Microsoft Research Silicon Valley Lab full time in 1995. There he worked on MyLifeBits, a database designed to capture all of his life’s information — articles, books, CDs, letters, emails, music, home movies, and videos — in a cloud-based digital database.

Mr. Bell is survived by his second wife, Sheridan Sinclaire-Bell, whom he married in 2009; his son, Brigham, and his daughter, Laura Bell, both from his first marriage; his stepdaughter, Logan Forbes; his sister, Sharon Smith; and four grandchildren.

In the 1985 Computerworld interview, Mr. Bell explained his formula for repeated technology successes. “The trick in any technology,” he said, “is knowing when to get on the bandwagon, knowing when to push for change, and then knowing when it’s dead and time to get off.”