assignment of read only variable error

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assignment of read-only variable ‘q’ when using const long #1798

ameli commented Jul 25, 2017 • edited

robertwb commented Jul 25, 2017

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TypeError: "x" is read-only

Valid cases, what went wrong.

The global variable or object property that was assigned to is a read-only property. (Technically, it is a non-writable data property .)

This error happens only in strict mode code . In non-strict code, the assignment is silently ignored.

Invalid cases

Read-only properties are not super common, but they can be created using Object.defineProperty() or Object.freeze() .

There are also a few read-only properties built into JavaScript. Maybe you tried to redefine a mathematical constant.

Sorry, you can't do that.

The global variable undefined is also read-only, so you can't silence the infamous "undefined is not a function" error by doing this:

Object.defineProperty()
Object.freeze()
"Which animals have three lungs?" on answers.com
Klingons (another answer to that query)

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Readonly class variables in C++

Readonly class variables in C++

TypeError: "x" is read-only

The JavaScript strict mode -only exception "is read-only" occurs when a global variable or object property that was assigned to is a read-only property.

What went wrong?

The global variable or object property that was assigned to is a read-only property. (Technically, it is a non-writable data property .)

This error happens only in strict mode code . In non-strict code, the assignment is silently ignored.

Invalid cases

Read-only properties are not super common, but they can be created using Object.defineProperty() or Object.freeze() .

There are also a few read-only properties built into JavaScript. Maybe you tried to redefine a mathematical constant.

Sorry, you can't do that.

The global variable undefined is also read-only, so you can't silence the infamous "undefined is not a function" error by doing this:

Valid cases

Object.defineProperty()
Object.freeze()

ValueError: assignment destination is read-only [Solved]

Last updated: Apr 11, 2024 Reading time · 2 min

# ValueError: assignment destination is read-only [Solved]

The NumPy "ValueError: assignment destination is read-only" occurs when you try to assign a value to a read-only array.

To solve the error, create a copy of the read-only array and modify the copy.

You can use the flags attribute to check if the array is WRITABLE .

Running the code sample produces the following output:

In your case, WRITEABLE will likely be set to False .

In older NumPy versions, you used to be able to set the flag to true by calling the setflags() method.

However, setting the WRITEABLE flag to True ( 1 ) will likely fail if the OWNDATA flag is set to False .

You will likely get the following error:

"ValueError: cannot set WRITEABLE flag to True of this array"

To solve the error, create a copy of the array when converting it from a Pillow Image to a NumPy array.

Passing the Pillow Image to the numpy.array() method creates a copy of the array.

You can also explicitly call the copy() method.

You can also call the copy() method on the Pillow Image and modify the copy.

The image copy isn't read-only and allows assignment.

You can change the img_copy variable without getting the "assignment destination is read-only" error.

You can also use the numpy.copy() method.

The numpy.copy() method returns an array copy of the given object.

The only argument we passed to the method is the image.

You can safely modify the img_copy variable without running into issues.

You most likely don't want to make changes to the original image.

Creating a copy and modifying the copy should be your preferred approach.

If you got the error when using the np.asarray() method, try changing it to np.array() .

Change the following:

To the following:

As long as the WRITEABLE flag is set to True , you will be able to modify the array.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

TypeError: Object of type ndarray is not JSON serializable
ValueError: numpy.ndarray size changed, may indicate binary incompatibility
NumPy RuntimeWarning: divide by zero encountered in log10
ValueError: x and y must have same first dimension, but have shapes

Borislav Hadzhiev

Web Developer

assignment of read-only variable m1a

#define trig 11 #define echo 12 const int m1a=5; const int m1b=6; const int m2a=9; const int m2b=10;

void setup() { Serial.begin(9600); pinMode(trig, OUTPUT); pinMode(echo, INPUT); }

void loop() {

long duration, distance; digitalWrite(trig, LOW); delayMicroseconds(2); digitalWrite(trig, HIGH); delayMicroseconds(10); digitalWrite(trig, LOW); duration = pulseIn(echo, HIGH); distance = (duration/2) / 29.1; if (distance < 10) { analogWrite(m1a=105); analogWrite(m1b=0); analogWrite(m2a=0); analogWrite(m2b=105); } else { analogWrite(m1a=110); analogWrite(m1b=0); analogWrite(m2a=110); analogWrite(m2b=0); } }

Check how analogWrite is supposed to be used.

And the problem is? in hiding with the code tags?

You are having problems with the syntax of the C programming language.

Google "C++ tutorial", pick any one of the tutorals online, and do the first few chpters of one of them..

No need to look further than top of page. Learning > Tutorials Learning > Reference is also good.

Error: Assignment of read-only location in C

Here, we are going to learn why an Error: Assignment of read-only location in C occurs and how to fixed in C programming language? By IncludeHelp Last updated : March 10, 2024

Error: Assignment of read-only variable in C

Error: assignment of read-only location occurs when we try to update/modify the value of a constant, because the value of a constant cannot be changed during the program execution, so we should take care about the constants. They are read-only.

Consider this example:

Here, the statement str[0]='p' will try to change the first character of the string, thus, the "Error: assignment of read-only location" will occur.

How to fix?

Do not change the value of a constant during program execution.

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Declare a Read-Only Variable with the const Keyword
assignment of read-only variable ‘q’ when using const long · Issue
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ES6 Declare a Read Only Variable with the const Keyword Learn

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C++ error: assignment of read-only variable
In your code you set up the parking variable with a const, this is telling the compiler that it will not be modified later.You then modify parking later by setting it to true or false. Using std::string is far more idiomatic c++ though. So I would do this instead:
c++
on compile i get main.cpp:56:24: error: assignment of read-only variable 'TIME' TIME = 3; ^ i want to change the TIME variable from main.h using a main.cpp function any help ? c++; Share. Improve this question ... The TIME variable is declared a const, so you will only be able to read its value but not modify it, ...
c++
Try changing your code to do this instead: static const bool testB = true; If you really want to change the value of it, you need to change how it is declared - perhaps something like this: static bool testB; // now you can change the value in whatever function you want. answered Jan 11, 2014 at 20:15. Krease. 16k 8 55 87.
Assignment of read-only variable error
Hi, so recently I just made this project but it doesn't seems to work.. it kept on saying the same thing, and that is "Assignment of read-only variable 'VAL'. I don't know what to do, so please check the code below and see if you can help me. const int A = 13; const int B = 12; const int C = 11; const int ON = 500; const int OFF = 0;
Error: Assignment of read-only variable in C
prog.c: In function 'main': prog.c:6:3: error: assignment of read-only variable 'a' a=100; ^ How to fix it? Assign value to the variable while declaring the constant and do not reassign the variable.
assignment of read-only variable
Read the QNH value only when the boolean is false and save it to another variable then set the boolean to true. Use the value in the second variable as the QNH in subsequent code. slipstick September 14, 2018, 10:03pm 5. Variables don't change value on their own. The best way to assign a value to QNH and have it remain constant is to note that ...
TypeError: "x" is read-only
The JavaScript strict mode-only exception "is read-only" occurs when a global variable or object property that was assigned to is a read-only property.
Assigning value to readonly variable during declaration
Generally though, you'd want to use. readonly c="$(( a + b ))" i.e. quoting the expansion. If the variable IFS has a value that includes the digit 2, it could otherwise lead to an empty value in c. The value would be empty as the shell would have split the arguments to readonly on the 2, resulting in the command. readonly c=.
assignment of read-only variable 'q' when using const long
test.c:1126:5: error: assignment of read-only variable 'q'. q -= ((r != 0) & ((r ^ b) < 0)); ^. error: command 'gcc' failed with exit status 1. It seems the type const long from the argument is directly translated into the intermediate variable q, where, q should be only long.
c++
2. Your first problem, the one the compiler is reporting, is that by default the value of local variables is what is captured by a block - which means the local variable cannot be modified by the block only its value used. If you add the __block modifier to a local variable then a block will capture the variable - which means the block sees the ...
TypeError: "x" is read-only
Message TypeError: "x" is read-only (Firefox) TypeError: 0 is read-only (Firefox) TypeError: Cannot assign to read only property 'x' of #<Object> (Chrome) TypeError ...
Readonly class variables in C++
No, it doesn't. I don't disagree with that. Well, there is a way to make it work without providing an assignment operator. You could encapsulate the read-only functionality in a separate class and overload the assignment operator of that class to do nothing. Then you can use that class to build classes with read-only variables without having to ...
Errors: Read-only
TypeError: "x" is read-only The JavaScript strict mode-only exception "is read-only" occurs when a global variable or object property that was assigned to is a read-only property. Message TypeError: Assignment to read-only properties is not allowed in strict mode (Edge) TypeError: "x" is read-only (Firefox) TypeError: 0 is read-only (Firefox) TypeError: Cannot assign to read only property 'x ...
Error: Assignment of read-only location in C
Error: Assignment of read-only variable in C. Error: assignment of read-only location occurs when we try to update/modify the value of a constant, because the value of a constant cannot be changed during the program execution, so we should take care about the constants. They are read-only. Consider this example: Example
c
8. In your function h you have declared that r is a copy of a constant Record -- therefore, you cannot change r or any part of it -- it's constant. Apply the right-left rule in reading it. Note, too, that you are passing a copy of r to the function h() -- if you want to modify r then you must pass a non-constant pointer. void h( Record* r)
ValueError: assignment destination is read-only [Solved]
The NumPy "ValueError: assignment destination is read-only" occurs when you try to assign a value to a read-only array. To solve the error, create a copy of the read-only array and modify the copy. You can use the flags attribute to check if the array is WRITABLE. main.py. from PIL import Image.
assignment of read-only variable
I am trying to measure an initial value of voltage (calculate an average value and multiply it 1.25x) and then compare it to following values for conductivity detection of isotachophoretic zones. I got difficulties to keep the initial value (A1) and use it later. It looks like a C++ issue but I did not find any help in C++ tutorials, although my problem must be trivial. I understand that local ...
assignment of read-only variable m1a
You are having problems with the syntax of the C programming language. Google "C++ tutorial", pick any one of the tutorals online, and do the first few chpters of one of them..
Error: 'else' without a previous 'if' in C
Error: Assign string to the char variable in C; Error: Assignment of read-only variable in C; Error: case label does not reduce to an integer constant in C; Error: duplicate case value in C; Error: Executing more than one case block in C; Error: switch quantity not an integer in C; Error: case label not within a switch statement in C
Error: Assignment of read-only variable in C
prog.c: In function 'main': prog.c:6:3: error: assignment of read-only variable 'a' a=100; ^ How to fix it? Assign value to the variable while declaring the constant and do not reassign the variable.
Error: Assignment of read-only location in C
Error: Assignment of read-only variable in C. Error: assignment of read-only location occurs when we try to update/modify the value of a constant, because the value of a constant cannot be changed during the program execution, so we should take care about the constants. They are read-only. Consider this example:

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assignment of read-only variable ‘q’ when using const long #1798

ameli commented Jul 25, 2017 • edited

robertwb commented Jul 25, 2017

TypeError: "x" is read-only

Invalid cases

Document Tags and Contributors

Readonly class variables in C++

TypeError: "x" is read-only

What went wrong?

Invalid cases

Valid cases

ValueError: assignment destination is read-only [Solved]

# ValueError: assignment destination is read-only [Solved]

# Additional Resources

Borislav Hadzhiev

assignment of read-only variable m1a

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Error: Assignment of read-only location in C

How to fix?

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