C strsep Function Usage

To avoid modifying the original string, one can utilize standard C string functions. Additionally, strings are widely utilized as common data structures, which accounts for the extensive range of associated functions available.
In every programming language, you can write codes that range from a very basic
complexity level
to a very high complexity level. Similarly, you also have to deal with multiple different data structures every time you come across a new problem at hand. Strings are also classified as one of the most commonly used data structures, and this is exactly why they have a very large number of different functions associated with them. The C programming language has a dedicated library that deals with all the functions related to strings, and in this particular article, we are going to explore one of the most important and useful functions of this library.

What is the “strsep” Function in C?

The C programming language utilizes the ”
” function to split strings. When coding in C, you often encounter lengthy strings that need to be tokenized based on a specific delimiter. In such cases, the ”
strsep” Function
” function is useful as it accomplishes the task for you. The primary objective of this function is to divide the given string into multiple chunks based on the logic of your C program. These divided chunks can then be stored in a database or used within the same program for various purposes.

Arguments of the “strsep” Function in C:

The general structure of the ”
strsep” function
” typically appears as:

# strsep(StringToBeSliced, Delimiter);

The function has two distinct arguments, as mentioned in the syntax above. The initial argument is the input string that you want to slice, while the second argument is the delimiter you want to use for the slicing.

To which Library does the “strsep” Function in C belong?

The “strsep” function is a part of the C programming language’s “string.h” library. By including this library in your C program, you can easily utilize the “strsep” function within it.

Implementation Example of the “strsep” Function in C:

In this section, we will guide you through a basic use-case of the C function called “strsep.” To comprehend this, take a look at the following C code example:

This C program begins by including the standard “stdio.h” library for input and output operations in the C programming language. Additionally, the “string.h” library is included, which contains the implementation of the “strsep” function mentioned earlier. The “main()” function declares two character type pointers named “string” and “chunk”. The first pointer points to the location of the string to be sliced, while the second pointer serves as a loop counter in the later part of the code. Lastly, the statement “strings = strdup(“Hello World! I am a string slice function!”)” is included.

In this statement, we utilized the ”
strdup” function
” from the “string.h” header file. This function copies the input string to a designated variable, which in this case is the “string” variable declared earlier through the implementation of the “strdup” function.

The code includes a “while” loop that repeatedly processes the “chunk” pointer until it no longer points to the
original string
string. The loop utilizes the “strsep” function to split the string based on the space delimiter, continuing until there are no characters remaining or the string becomes “NULL”. During each iteration of the loop, the value of the “chunk” variable is printed. This variable stores the characters before the specified delimiter. The code concludes with the “return 0” statement.

In order to compile the C code, we had to use the command displayed as follows:

$ gcc SliceString.


–o SliceString

After compiling the code successfully and ensuring that no error messages are generated, the subsequent action involves executing it by using the given command.

$ .



In the provided image, the output of the C program demonstrates that our given string has been divided based on the designated space delimiter. Each word is then displayed as an individual string on its own line.

We were curious about the functionality of this function when a delimiter other than space is used. Consequently, we made slight modifications to our existing C program, which can be seen in the provided image below.

The program depicted in the above image is identical to the one we discussed previously, with the only variation being the substitution of the space delimiter with
exclamation mark
this time.

When we compiled and executed the C program, the provided string was divided based on the exclamation mark delimiter, as depicted in the image. In the output, all the exclamation marks were eliminated from
input string
, while the remaining characters remained unchanged. Additionally, the removal of exclamation marks from our string caused line breaks in the output.

In order to further examine the functionality of the “strsep” function with a non-space delimiter, we experimented with a different delimiter by utilizing the provided C code.

The program depicted in the above image is identical to the one previously discussed, except for the alteration of the delimiter from an exclamation mark to the character “a” in this instance.

After compiling and running the C program, the given string was divided using the “a” character as a delimiter, as depicted in the image below. In the resulting output, all instances of the “a” character were eliminated from the input string, while preserving the rest of the characters. Additionally, the removal of the “a” character from our string caused line breaks in the output.


The main purpose of this guide is to discuss the “strsep” function in the C programming language. We provided a brief introduction to this function, explaining its purpose in the C language. Additionally, we presented the general syntax of the “strsep” function and elaborated on the various arguments it accepts.

Following that, we initiated the C library or the header file associated with this specific function. Subsequently, we provided you with a simple illustration that employs this function in C to divide a given string based on a specified delimiter. Later on, we proceeded to discuss various versions of the same example, altering the delimiter each time. Once you grasp the entirety of this discourse regarding the implementation of the “strsep” function, you will be capable of creating C programs that employ this function to slice strings.

Frequently Asked Questions