Split String in C programming using strtok_r() | Parsing CSV File

For example, you have a string sentence “CSEstack is a programming portal”. You want to get each word from the sentence like “CSEstack”, “is”, “a”, “programming” and “portal.”. This can be done by splitting the sentence and storing them.

You can use function strtok_r() to split the sentence in C/C++ programming.

About function  strtok_r() in C/C++

Input parameter to the strtok_r() function:

• a string which you want to split
• delimiter to distinguish and split the string
• address of the sentence you want to split

How does it work?

strtok_r() returns the token pointing to the next substring after delimiter. Calling function strtok_r() in a loop will give us all the sub-strings after splitting.

Split String in C Programming using strtok_r()

Check the below program.

// C program to demonstrate working of strtok_r() 
// by splitting string based on space character. 
#include <stdio.h> 
#include <string.h> 

int main() 
{ 
   char strToSplit[] = "CSEstack is a programming portal";

   char *token;
   int i=0;
   char *strArr[5] = {0};
   char* strSplit = strToSplit;
   while ((token = strtok_r(strSplit , " ", &strSplit)))
       strArr[i++] = token;

   for(int i=0; i<5; i++)
       printf("\n ++i) %s",strArr[i]);
}

In the above program, the delimiter is space ” “.  So, The string between two spaces will be considered as one token.

Output:

1) CSEstack
2) is
3) a
4) programming
5) portal

After splitting the string, you can also store the data in the array.

Where you can use strtok_r()?

Use Cases:

• If you are working on any networking project, you can concatenate all the payload. Send it to another device and split the payload.
• In networking, you can also use this function to split the IP address.
• It can also be useful for sending the grouped data using CGI variable.

Using strtok_r() for Parsing CSV file

CSV (comma separated value) is a special type of data structure where we can save the different data entities separated by a comma.

Example:

Name,Age,profession
Steve,34,developer
Noob,55,tester
Clave,32,designer

You can simply read the CSV file and loop over each line to get the name, age and profession of the employee by using strtok_r(). Here, delimiter will be ‘,’ instead of space.

// C program to demonstrate working of strtok_r() 
// by splitting string based on space character. 
#include <stdio.h> 
#include <string.h> 

int main() 
{ 
   char strEmpData[] = "Steve,34,developer";

   char *token;
   int i=0;
   char *strArr[3] = {0};
   char* strSplit = strEmpData;
   while ((token = strtok_r(strSplit , ",", &strSplit)))
       strArr[i++] = token;
 
  printf("\n Name: %s",strArr[0]);
  printf("\n Age: %d",atoi(strArr[1]));
  printf("\n Profession: %s",strArr[2]);
}

Output:

Name: Steve
Age: 34
Profession: developer

Related String Program in C:

• Difference Between Array and String in Programming
• C Program to Remove White Spaces from String

Any question or point to discuss this code to split String in C programming, write in the comment section.

Aniruddha Chaudhari

I am a Python enthusiast who loves Linux and Vim. I hold a Master of Computer Science degree from NIT Trichy and have 10 years of experience in the IT industry, focusing on the Software Development Lifecycle from Requirements Gathering, Design, Development to Deployment. I have worked at IBM, Ericsson, and NetApp, and I share my knowledge on CSEstack.org.