Linux bash string to int

How to Evaluate Strings as Numbers in Bash

Like everything is file in Linux, everything is string in bash.

Yes! Technically, there are no data types in Bash. Essentially, Bash variables are just character strings.

And that creates a problem when you are trying to do arithmetic operations in bash. The numbers you try to add give you weird results.

To convert strings to integers in bash, wrap them in $((X)). Like this:

If the string has an identifiable number, it will be treated as a number. The example I showed above can be corrected as:

Let’s see the conversion of strings into numbers in a bit more detail so that you can use arithmetic calculations in bash.

Converting string variables to numbers

Let’s declare some «numbers» which are basically strings of characters.

You can check the assigned number:

Let’s now try to add both numbers and store the value in a third variable c :

As you can see on the output above, c is also being treated as a string.

To make the addition successful, you need to “convert” it through an arithmetic expansion:

Do note that c is still actually a string, until you implicitly use the same arithmetic expansion again for another operation that I’ll discuss in a while.

The above is equivalent to:

Let’s use a third variable d for another operation:

All these implicit declarations are still strings. It is same as how I had defined a and b earlier.

Now for the second operation:

In the above expression, the product of b and c is calculated first and finally the addition and subtraction follow.

As I mentioned previously, anything you do between $((. )) is considered to be an arithmetic operation.

Try mixing actual strings and numbers

Mixing strings and integers is still safer than mixing coke and mint. It does produce a weird result, though.

It will only work when there are numbers (as string). If it is pure character string, it won’t be magically converted into some numbers. Instead, it is ignored as you can see in the example above.

Alternate method: use expr

You can also use the expr tool to do the evaluation, but do note that it is not a “native” Bash procedure, as you need to have coreutils installed (by default on Ubuntu) as a separate package.

I hope this quick little tutorial helped you in evaluating bash strings as numbers. If you have questions or suggestions, feel free to leave a comment below.

Источник

bash: преобразовать строку в int &, если int> #

Я хотел бы иметь bash-скрипт, который проверяет, есть ли в файле более # строк, но у меня еще нет правильной работы, и я не уверен, как это сделать. Я никогда не использовал Bash раньше.

Сейчас я использую: linesStr=$(cat log | wc -l) , чтобы получить количество строк в файле (ожидайте, что это будет строка). когда я слышу эхо, это дает мне число 30, которое является правильным.

Но поскольку это, скорее всего, строка, она не выполняет оператор if, поэтому мне нужно преобразовать linesStr в int с именем linesInt.

У меня также есть ощущение, что само выражение if сделано неправильно.

Буду признателен, если кто-нибудь может дать мне простое решение для начинающих.

4 ответа

1. Нет необходимости в cat .
2. Недостаток пробелов вокруг [ и ] .
3. Используйте оператор сравнения чисел вместо оператора перенаправления.

Вот рабочий скрипт.

Нет строковых или целочисленных типов для преобразования. Проблема в том, что вы используете неправильный оператор сравнения. Для числового сравнения используйте if [ $linesStr -gt 29 ] . Прочитайте man bash раздел CONDITIONAL EXPRESSIONS для доступных операторов.

Ваш блок кода if неправильный if [$linesStr > 29] , после [ и до ] должен быть пробел

Желательно, чтобы вы всегда использовали [[ ]] с оператором if, а не [ ] . Всякий раз, когда вы хотите сравнить целые числа, не используйте > или , используйте -gt -ge -lt -le . И если вы хотите выполнить какое-либо математическое сравнение, рекомендуется использовать (( )) .

Вы также должны заметить, что вам не нужны операторы сравнения bash или получение значения переменной с $ при использовании (( ))

Источник

Из string в int

Переменная содержит строчку, которая равна числу. Ищу ошибку, возможно она в этом

Создайте класс Animal. Добавьте поля string Name, string Kind, string Areal, int Population
Создайте класс Animal. Добавьте поля string Name, string Kind, string Areal, int Population.

Создайте класс Animal. Добавьте поля string Name, string Kind, string Areal, int Population
Здравствуйте! По C# есть задачка, с которой я так и не разобрался 🙁 Задача: Создайте.

Ошибки: Cannot implicitly convert type ‘string’ to ‘int’ и Argument 1: cannot convert from ‘int’ to ‘string’
youtube.com_Пишем парсер на Csharp. Ошибка Пытаюсь написать парсер. Вроде сделал всё как в.

Marinero, Другого ответа ему и не нужно 😀

Помощь в написании контрольных, курсовых и дипломных работ здесь.

Dictionary , Dictionary > dict — возможно ли?
Собственно вопрос в заголовке. Возможно ли использовать объект вида.

Получить значение value (string) из Dictionary
Имеем Dictionary pos = new Dictionary ; pos.Add(1,»A»);.

Разбиение String массива на int и String массивы
так-с. из файла я записал в массив tempmas слова, например «0PlPs1» или «1VKG». нужно брать слово.

Реализация функции char *padl(const char *string, int len, int c=’ ‘)
Реализовать функцию возвращающую указатель на новую строку длины len, полученную из string либо.

Как вставить элемент и вывести элементы на экран в map > ?
У меня есть map >, в него надо добавить элементы (типа Ivanov potato 200).

Какая из этих функций int Q(int w) int W(int y,int u,int i) сработает быстрее?
Если есть 2 функции(простые или перегруженные) к примеру Q(int w) int W(int y,int u,int i)или int.

Источник

Bash Beginner Series #6: String Operations in Bash

Let’s manipulate some strings!

If you are familiar with variables in bash, you already know that there are no separate data types for string, int etc. Everything is a variable.

But this doesn’t mean that you don’t have string manipulation functions.

In the previous chapter, you learned arithmetic operators in Bash. In this chapter, you will learn how to manipulate strings using a variety of string operations. You will learn how to get the length of a string, concatenate strings, extract substrings, replace substrings, and much more!

Get string length

Let’s start with getting the length of a string in bash.

A string is nothing but a sequence (array) of characters. Let’s create a string named distro and initialize its value to “Ubuntu”.

Now to get the length of the distro string, you just have to add # before the variable name. You can use the following echo statement:

Do note that echo command is for printing the value. <#string>is what gives the length of string.

Concatenating two strings

You can append a string to the end of another string; this process is called string concatenation.

To demonstrate, let’s first create two strings str1 andstr2 as follows:

Now you can join both strings and assign the result to a new string named str3 as follows:

It cannot be simpler than this, can it?

Finding substrings

You can find the position (index) of a specific letter or word in a string. To demonstrate, let’s first create a string named str as follows:

Now you can get the specific position (index) of the substring cool. To accomplish that, use the expr command:

The result 9 is the index where the word “Cool” starts in the str string.

I am deliberately avoiding using conditional statements such as if, else because in this bash beginner series, conditional statements will be covered later.

Extracting substrings

You can also extract substrings from a string; that is to say, you can extract a letter, a word, or a few words from a string.

To demonstrate, let’s first create a string named foss as follows:

Now let’s say you want to extract the first word “Fedora” in the foss string. You need to specify the starting position (index) of the desired substring and the number of characters you need to extract.

Therefore, to extract the substring “Fedora”, you will use 0 as the starting position and you will extract 6 characters from the starting position:

Notice that the first position in a string is zero just like the case with arrays in bash. You may also only specify the starting position of a substring and omit the number of characters. In this case, everything from the starting position to the end of the string will be extracted.

For example, to extract the substring “free operating system” from the foss string; we only need to specify the starting position 12:

Replacing substrings

You can also replace a substring with another substring; for example, you can replace “Fedora” with “Ubuntu” in the foss string as follows:

Let’s do another example, let’s replace the substring “free” with “popular”:

Since you are just printing the value with echo command, the original string is not reallt altered.

Deleting substrings

You can also remove substrings. To demonstrate, let’s first create a string named fact as follows:

You can now remove the substring “big” from the string fact:

Let’s create another string named cell:

Now let’s say you want to remove all the dashes from the cell string; the following statement will only remove the first dash occurrence in the cell string:

To remove all dash occurrences from the cell string, you have to use double forward slashes as follows:

Notice that you are using echo statements and so the cell string is intact and not modified; you are just displaying the desired result!

To modify the string, you need to assign the result back to the string as follows:

Converting upper and lower-case letters in string

You can also convert a string to lowercase letter or uppercase letters. Let’s first create two string named legend and actor:

You can convert all the letters in the legend string to uppercase:

You can also convert all the letters in the actor string to lowercase:

You can also convert only the first character of the legend string to uppercase as follows:

Likewise, you can convert only the first character of the actor string to lowercase as follows:

You can also change certain characters in a string to uppercase or lowercase; for example, you can change the letters j and n to uppercase in the legend string as follows:

Awesome! This brings us to the end of this tutorial in the bash beginner series. I hope you have enjoyed doing string manipulation in bash and stay tuned for next week as you will learn how to add decision-making skills to your bash scripts!

Источник

Bash Convert Integer To String

Related Searches

Listing Of Websites About bash convert integer to string

linux — Convert an output to string — Stack Overflow

Posted at: 1 week ago | Categories: FAQs | 426 People Used View Detail

integer to string — UNIX

URL: https://www.unix.com/. /126104-integer-string.html Go now

Posted at: 1 day ago | Categories: FAQs | 245 People Used View Detail

Argument string to integer in bash — Unix & Linux Stack .

Posted at: 1 week ago | Categories: FAQs | 431 People Used View Detail

How to Convert Strings into Numbers in Bash

$ b=3. You can check the assigned number:

Posted at: 1 week ago | Categories: FAQs | 172 People Used View Detail

Bash Variable in String | Learn the Example of Bash .

Posted at: 1 week ago | Categories: FAQs | 189 People Used View Detail

In bash shell script how do I convert a string to an number

Posted at: 4 days ago | Categories: FAQs | 400 People Used View Detail

unix — How to convert a variable to string format? KSH .

Posted at: 1 week ago | Categories: FAQs | 102 People Used View Detail

Converting string to integer in BASH

Posted at: 1 week ago | Categories: FAQs | 189 People Used View Detail

String Manipulation in Bash with examples | UnixUtils

Posted at: 4 days ago | Categories: FAQs | 176 People Used View Detail

shell — BASH base conversion from decimal to hex — Unix .

Posted at: 1 week ago | Categories: FAQs | 467 People Used View Detail

bash — How to convert floating point number to integer .

Posted at: 2 days ago | Categories: FAQs | 255 People Used View Detail

Bash Convert Number To String — realestatefind.info

$ a=11 [email protected]:

$ b=3. Verified: 6 days ago Show List Real Estate

Posted at: 1 week ago | Categories: FAQs | 143 People Used View Detail

Conversion hex string into ascii in bash command line .

Posted at: 6 days ago | Categories: FAQs | 261 People Used View Detail

Converting a decimal into integer — unix.com

URL: https://www.unix.com/. /44626-converting-decimal-into-integer.html Go now

Posted at: 1 week ago | Categories: FAQs | 98 People Used View Detail

Java Convert int to String — javatpoint

Posted at: 5 days ago | Categories: FAQs | 130 People Used View Detail

Convert string number to a integer — UNIX

Posted at: 1 day ago | Categories: FAQs | 451 People Used View Detail

[SOLVED] Converting string to number in bash

Posted at: 1 week ago | Categories: FAQs | 332 People Used View Detail

Bash String To Integer — imageslink.org

Posted at: 2 days ago | Categories: FAQs | 196 People Used View Detail

Bash Convert String To Hex — imageslink.org

Posted at: 1 week ago | Categories: FAQs | 369 People Used View Detail

Convert String To Integer Bash Images

Posted at: 6 days ago | Categories: FAQs | 302 People Used View Detail

bash scripting: converting integer to decimal

Posted at: 1 day ago | Categories: FAQs | 362 People Used View Detail

Bash split string into array using 4 simple methods .

Posted at: 6 days ago | Categories: FAQs | 126 People Used View Detail

Related Searches

How to convert a string to integer?

In C#, you can convert a string representation of a number to an integer using the following ways: Parse () method Convert class TryParse () method — Recommended

How to compare strings in Bash?

When comparing strings in Bash you can use the following operators:string1 = string2 and string1 == string2 — The equality operator returns true if the operands are equal. . string1 != string2 — The inequality operator returns true if the operands are not equal.string1 =

regex — The regex operator returns true if the left operand matches the extended regular expression on the right. More items.

How do I convert a string to a number in Python?

Python:Convert a String to a Number. You can use the functions int and float to convert to integers or floating point numbers. The value «1234» is a string, you need to treat it as a number — to add 1, giving 1235.

How do I convert a string to an int in Java?

The most direct solution to convert a string to an integer is to use the parseInt method of the Java Integer class. parseInt converts the String to an int, and throws a NumberFormatException if the string can’t be converted to an int type.

Источник