# Count words in a given string

Given a string, count number of words in it. The words are separated by following characters: space (‘ ‘) or new line (‘\n’) or tab (‘\t’) or a combination of these.

## Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

There can be many solutions to this problem. Following is a simple and interesting solution.
The idea is to maintain two states: IN and OUT. The state OUT indicates that a separator is seen. State IN indicates that a word character is seen. We increment word count when previous state is OUT and next character is a word character.

## C/C++

/* C/C++ program to count no of words from given input string. */
#include <stdio.h>

#define OUT    0
#define IN    1

// returns number of words in str
unsigned countWords(char *str)
{
int state = OUT;
unsigned wc = 0;  // word count

// Scan all characters one by one
while (*str)
{
// If next character is a separator, set the
// state as OUT
if (*str == ' ' || *str == '\n' || *str == '\t')
state = OUT;

// If next character is not a word separator and
// state is OUT, then set the state as IN and
// increment word count
else if (state == OUT)
{
state = IN;
++wc;
}

// Move to next character
++str;
}

return wc;
}

// Driver program to tes above functions
int main(void)
{
char str[] = "One two         three\n    four\tfive  ";
printf("No of words : %u", countWords(str));
return 0;
}

## Java

/* Java program to count no of words
from given input string. */
public class GFG {

static final int OUT = 0;
static final int IN = 1;

// returns number of words in str
static int countWords(String str)
{
int state = OUT;
int wc = 0;  // word count
int i = 0;

// Scan all characters one by one
while (i < str.length())
{
// If next character is a separator, set the
// state as OUT
if (str.charAt(i) == ' ' || str.charAt(i) == '\n'
|| str.charAt(i) == '\t')
state = OUT;

// If next character is not a word separator
// and state is OUT, then set the state as IN
// and increment word count
else if (state == OUT)
{
state = IN;
++wc;
}

// Move to next character
++i;
}
return wc;
}

// Driver program to test above functions
public static void main(String args[])
{
String str = "One two       three\n four\tfive  ";
System.out.println("No of words : " + countWords(str));
}
}
// This code is contributed by Sumit Ghosh

## Python

# Python program to count words in a given string
OUT = 0
IN = 1

# Returns number of words in string
def countWords(string):
state = OUT
wc = 0

# Scan all characters one by one
for i in xrange(len(string)):

# If next character is a separator, set the
# state as OUT
if (string[i] == ' ' or string[i] == '\n' or
string[i] == '\t'):
state = OUT

# If next character is not a word separator
# and state is OUT, then set the state as
# IN and increment word count
elif state == OUT:
state = IN
wc+=1

# Return the number of words
return wc

# Driver program
string = "One two         three\n  four\tfive  "
print "No. of words : " + str(countWords(string))

# This code is contributed by BHAVYA JAIN

Output:
No of words : 5

Time complexity: O(n)

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