Step by Step solution about How to resolve the algorithm Tokenize a string step by step in the C programming language

The provided C code demonstrates string tokenization using the strtok() function and a custom tokenize() function with a callback. Here's a detailed explanation:

strtok() Function Example:

• It defines an array of character pointers a to hold the tokenized strings.

• It initializes a string s with the sentence "Hello,How,Are,You,Today."

• It uses strdup() to create a duplicate of the string s. This is done because strtok() modifies the original string, so a copy is made to prevent any unintended changes.

• It calls strtok() to tokenize the string s with "," as the delimiter. The first call to strtok() with ds initializes the tokenization process. Subsequent calls to strtok() with NULL as the first argument continue tokenizing the string.

• It stores the tokenized strings in the array a and increments the counter n for each token. It stops when n reaches 4 or when there are no more tokens.

• Finally, it prints the tokenized strings with periods "." and a newline.

Custom tokenize() Function with Callback:

• It re-implements the string tokenization using a custom function called tokenize(). The function takes three arguments: s (input string), delim (delimiter character), and cb (callback function).

• The callback function doprint() is defined to simply print the tokens with a period ".".

• The tokenize() function uses a while loop to iterate through the input string s and find tokens. It uses the delim character as the delimiter to separate tokens.

• Inside the while loop, it uses a bitwise XOR trick to toggle the delimiter character at the end of each token, effectively isolating the token.

• It then calls the callback function cb to process the isolated token, which in this case is doprint() to print the token.

• After processing a token, it toggles the delimiter character back using the bitwise XOR and advances the s pointer to the next character.

• This process continues until the end of the string is reached or until no more tokens are found.

• In the main function, it calls the tokenize() function with the input string array and the ',' delimiter. The doprint() function is used as the callback to print the tokens.

#include<string.h>
#include<stdio.h>
#include<stdlib.h>

int main(void)
{
	char *a[5];
	const char *s="Hello,How,Are,You,Today";
	int n=0, nn;

	char *ds=strdup(s);

	a[n]=strtok(ds, ",");
	while(a[n] && n<4) a[++n]=strtok(NULL, ",");

	for(nn=0; nn<=n; ++nn) printf("%s.", a[nn]);
	putchar('\n');

	free(ds);

	return 0;
}


#include<stdio.h>

typedef void (*callbackfunc)(const char *);

void doprint(const char *s) {
	printf("%s.", s);
}

void tokenize(char *s, char delim, callbackfunc cb) {
	char *olds = s;
	char olddelim = delim;
	while(olddelim && *s) {
		while(*s && (delim != *s)) s++;
		*s ^= olddelim = *s; // olddelim = *s; *s = 0;
		cb(olds);
		*s++ ^= olddelim; // *s = olddelim; s++;
		olds = s;
	}
}

int main(void)
{
        char array[] = "Hello,How,Are,You,Today";
	tokenize(array, ',', doprint);
	return 0;
}