C library - strtok() function

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The C Library strtok() function is used for tokenizing strings. These strings are a set of tokens using delimiters/separators characters. In general, tokens are usually words, phrases, or individual characters within a string.

Here, char *strtok(char *str, const char *delim) breaks string str into a series of tokens using the delimiter delim.

Syntax

Following is the syntax of the C library strtok() function −

 char *strtok(char *str, const char *delim) 

Parameters

This funtion accepts the following parameter −

• str − The contents of this string are modified and broken into smaller strings(tokens).

• delim − This is the C string containing the delimiters. These may vary from one call to another.

Return Value

This function returns a pointer to the first token found in the string. A null pointer is returned if there are no tokens left to retrieve.

Example 1

Following is the C program that illustrates the usage of strtok() function.

 #include <string.h> #include <stdio.h> int main () { char str[80] = "This is - www.tutorialspoint.com - website"; const char s[2] = "-"; char *token; /* get the first token */ token = strtok(str, s); /* walk through other tokens */ while( token != NULL ) { printf( " %s\n", token ); token = strtok(NULL, s); } return(0); } 

Output

On execution of above code, we get the following result −

 This is www.tutorialspoint.com website 

Example 2

In this example, we demonstrates each substring of the string is represented in a new line using strtok() function.

 #include <stdio.h> #include <string.h> int main() { char stng[100] = "Welcome to C Programming"; char *res; res = strtok(stng, " "); while(res != NULL) { printf("%s \n", res); res = strtok(NULL, " "); } return 0; } 

Output

After executing the above code, the outcome becomes −

 Welcome to C Programming 

Example 3

Following is the C program that demonstrates how to returns the null pointer using strtok() function.

 #include <stdio.h> #include <string.h> int main() { //String i.e. break in token char str_1[] = "ttttt"; //delimiter char *str_2 = "tp"; // initial call of strtok char *token = strtok(str_1, str_2); printf("The resultant token is %s\n", token); return 0; } 

Output

The above code produces the following result −

 The resultant token is (null)