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In programming languages, the length or size of a data type plays an important role. It helps in list traversal and facilitates the extraction of useful information.

The length is especially important when performing tasks that require traversing the entire string. Therefore, considering the importance of the length or size of any data type, we will learn different ways to calculate the length of a string.

String length and base symbols

A string is a sequence of distinct characters, which may include spaces. In Bash, the length of a string is the total number of characters in the string.

For example, the "Hello World" string contains ten characters and one space. Therefore, its length is eleven.

Most scripting and programming languages ​​have built-in or library functions for finding the length of a string. Likewise, in Bash there are many ways to manipulate Bash commands to calculate the length of a string.

Calculate string length using the # operator in Bash

We can use the # operator to calculate the length of a string. The following code shows the syntax to get the length of a string using the # operator.

${#your_var}

First, we enclose the variable containing the string in curly braces and precede the variable with the # operator.

#The operator plays a vital role in printing the length of the string. Without using #, the code will print the entire string, so adding it to a variable is essential.

Also, the outer $ sign treats the string length as a variable and prints it to the screen using the echo command. The following code shows how to calculate the length of a string using #.

var="hello world"
echo ${var}
echo ${#var}

In line 1, we create a variable named var. The var variable can contain any string from the terminal or a file string.

The second line prints the entire string using $ and curly braces. In the last line, we use the # symbol with a variable and get the length of the string printed on the command console.

Calculate the length of a string using the expr command in Bash

Here, we will explore the use of expr command to calculate the length of a string. The following code describes the basic syntax of using expr command.

`expr "$var1" : "$var2"`

The expr command takes two arguments: before and after a comparison operator:. Comparison operators compare the common characters of two strings and return the number of similar characters.

In var1, we give the string whose length needs to be calculated. var2 contains a regular expression that parses the string one by one, and the comparison operator calculates the count of each similar character.

The following code demonstrates an example.

var="hello world"
echo `expr "$var" : ".*"`

In the code above, we assign the string "hello world" to the variable var. .* will resolve all characters of the previous token (i.e. the value of var).

Thus, with two identical operands, the comparison operator returns the total number of characters in the first operand.

Calculate the length of a string using awk command in Bash

Let us calculate the length of a string using the awk command. The awk command is a scripting language used for data manipulation and report generation.

The following code demonstrates the use of awk command to calculate the length of a string.

var="hello world"
n1=`echo $var |awk '{print length}'`
echo $n1

In the above code, we have used awkthe built-in properties of and the print command.

The awk command uses pipes to get input as a string from the var variable. Pipes send the command output to the input after the pipe.

Line 3 prints the length of the string as confirmation.

Calculate string length using wc command in Bash

Now we will explore the length calculation of a string using the command. We just pipe the string to wcwith the flag -c or -mwc and we will get the desired output (i.e. the length of the string).

The following Bash command uses the wc command to display the length of a string.

echo -n "$var" | wc -c

or:

echo -n "$var" | wc -m

The above code shows the use of two different flags of the wc command to calculate the length of a string.

If we use only wc command, it will provide more information than string length which is not necessary. So, mentioning flag after wc command is inevitable.

There are two flags we can use, -c or -m. Both return the same output.

The following snippet shows the output of the above wc code.

Calculate the length of a file in characters

Now we will discuss how to calculate the length of a string from a file. We will create a file named abc.txt and write some text into it.

We will then read from the file and print the length of the string.

The following code shows the calculation of string length from a file.

touch abc.txt
echo "hello world">> abc.txt
cat abc.txt | wc -c

touchA new file abc.txt is created and we write a hello world string to it using simple I/O redirection. The cat command in line 3 displays the contents of abc.txt.

However, the pipe |makes catthe output of the command wcthe input of the command. Therefore, wc will count the words in this output.