The easy way to do this is to use the str() function
The powerful way to do this is to use the % string formatting operator
Number to String by str
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Creating a string
The
% operator takes a format string and an argument or tuple ofarguments. The format string includes %d spaceswhere the integers should go or %f places for the floating point numbers.
We can specify the total number of characters to use (the number isright justified in this space). We can specify the number of decimal placesto use.
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In this tutorial, we will learn how to convert a string variable to an integer or a float in Python programming language. Python automatically assigns the data type according to the data stored in the variable. Sometimes we have to store a value as a string in a variable and then we need to calculate the sum of this variable with other numeric variables. In that case, we need to convert the string to an integer value (if we know that it will be integer always). For example, take a look at the below program :
The first variable ‘first_number’ is a string variable and the second variable ‘second_number’ is an integer variable. The program is trying to add both of these variables.
Gta 3 ram pages map ps2. But we can’t add a string variable with an integer. So, this program will throw one error like below :
As you can see, the error is a ‘TypeError’ and the description of this error is that it can’t add one string object with an integer object. To fix this error, we will have to convert the string first_number to an integer variable.
This is the title of this tutorial and we will learn how to convert a number represented as a string to an integer. We will also learn what will happen if we can’t convert.
Python program to convert a string to an integer :
The conversion is simpler than you think. Python has one built-in function called int() to make this conversion. Wrap the string value with int() and it will return the integer representation of the string. Let’s take a look :
It will print 3 as the output.
The first variable is a string “1”. Using int() will convert it to an integer and we can add it to the other integer ‘2’. But, what will be the result if the string first_number holds a different value than a number like below :
As you can see it throws one ‘ValueError’ with a message ‘invalid literal for int() with base 10’. ‘1@‘ is not a valid decimal number. Thus ‘int()’ method can’t convert it.
The best way to handle cases like this is to use one try-catch block like below :
It will print the exception error.
Try-catch blocks are useful for handling code blocks that may throw an exception. It will first try to run the code defined inside the ‘try’ block. If an exception is raised, it will exit from the try block and run the code defined inside the catch block.
The catch block is normally used for printing out the error message to the developer. It makes the debugging easy.
Conclusion :
Converting a string to an integer is one of the most commonly faced problems in python development. For example, if your server is running on python and it is accepting integer values represented as String, we can use int() for the conversion.
But if it receives any other string values instead of an integer, the server will stop. As mentioned above, you can use try-catch and return one error message to the application in such scenarios.
Also check
How can I convert a string of bytes into an int in python?
Say like this:
'yxccxa6xbb'
I came up with a clever/stupid way of doing it:
I know there has to be something builtin or in the standard library that does this more simply..
This is different from converting a string of hex digits for which you can use int(xxx, 16), but instead I want to convert a string of actual byte values.
UPDATE:
I kind of like James' answer a little better because it doesn't require importing another module, but Greg's method is faster:
My hacky method:
FURTHER UPDATE:
Someone asked in comments what's the problem with importing another module. Well, importing a module isn't necessarily cheap, take a look:
Including the cost of importing the module negates almost all of the advantage that this method has. I believe that this will only include the expense of importing it once for the entire benchmark run; look what happens when I force it to reload every time:
Needless to say, if you're doing a lot of executions of this method per one import than this becomes proportionally less of an issue. It's also probably i/o cost rather than cpu so it may depend on the capacity and load characteristics of the particular machine.
jww
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ʞɔıuʞɔıu
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11 AnswersZitrax
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Greg HewgillGreg Hewgill
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In Python 3.2 and later, use
or
according to the endianness of your byte-string.
This also works for bytestring-integers of arbitrary length, and for two's-complement signed integers by specifying
signed=True . See the docs for from_bytes .
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Mechanical snailMechanical snail
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As Greg said, you can use struct if you are dealing with binary values, but if you just have a 'hex number' but in byte format you might want to just convert it like:
..this is the same as:
..except it'll work for any number of bytes.
James AntillJames Antill
I use the following function to convert data between int, hex and bytes.
Source: http://opentechnotes.blogspot.com.au/2014/04/convert-values-to-from-integer-hex.html
JrmJrm
Warning: the above is strongly platform-specific. Both the 'I' specifier and the endianness of the string->int conversion are dependent on your particular Python implementation. But if you want to convert many integers/strings at once, then the array module does it quickly.
Rafał DowgirdRafał Dowgird
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In Python 2.x, you could use the format specifiers
<B for unsigned bytes, and <b for signed bytes with struct.unpack /struct.pack .
E.g:
Let
x = 'xffx10x11'
And:
That
* is required!
See https://docs.python.org/2/library/struct.html#format-characters for a list of the format specifiers.
tripleee
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TetraluxTetralux
Test 1: inverse:
Test 2: Number of bytes > 8:
Test 3: Increment by one:
Test 4: Append one byte, say 'A':
Test 5: Divide by 256:
Result equals the result of Test 4, as expected.
user3076105user3076105
How To Convert String To Float Python
I was struggling to find a solution for arbitrary length byte sequences that would work under Python 2.x. Finally I wrote this one, it's a bit hacky because it performs a string conversion, but it works.
This function has two requirements:
Of course, this should be used only if arbitrary length is needed. Otherwise, stick with more standard ways (e.g.
struct ).
Andrea LazzarottoAndrea Lazzarotto
int.from_bytes is the best solution if you are at version >=3.2.The 'struct.unpack' solution requires a string so it will not apply to arrays of bytes.Here is another solution:
hex( bytes2int( [0x87, 0x65, 0x43, 0x21])) returns '0x87654321'.
Max payne 3 highly compressed direct download. It handles big and little endianness and is easily modifiable for 8 bytes
user3435121user3435121
As mentioned above using abdullahselekabdullahselek
unpack function of struct is a good way. If you want to implement your own function there is an another solution:
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Python Convert Int To String Base
A decently speedy method utilizing array.array I've been using for some time:
predefined variables:
to int: (read)
from int: (write)
It's possible these could be faster though.
EDIT:
For some numbers, here's a performance test (Anaconda 2.3.0) showing stable averages on read in comparison to reduce() :
Python Convert Int To String In List
This is a raw performance test, so the endian pow-flip is left out.
The shift function shown applies the same shift-oring operation as the for loop, and arr is just array.array('B',[0,0,255,0]) as it has the fastest iterative performance next to dict .
Why does fallout 4 keep crashing. I should probably also note efficiency is measured by accuracy to the average time.
TcllTcll
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