Question

I need convert this java code to C language. There is no string can be used in C. Thank you!

import java.util.Scanner;

public class Nthword
{
public static void main( String args[] )
{
String line;
int word;
Scanner stdin = new Scanner(System.in);

while ( stdin.hasNextLine() )
{
line = stdin.nextLine();
word = stdin.nextInt(); stdin.nextLine(); // get rid of the newline after the int

System.out.println( "Read line: \"" + line + "\", extracting word [" + word + "]" );
System.out.println( "Word #" + word + " is: " + extractWord( line, word ) );
}

stdin.close();

System.out.println( "\nEnd of processing" );
  
}

// returns the first word of the string
private static String extractWord( String theLine, int word )
{
int start;
int end;
int spaces = 1;
String result = "";

// search for the nth non-blank character
for (start = 0; start < theLine.length() && spaces < word; start++)
{
if ( Character.isSpaceChar( theLine.charAt( start ) ) )
{
spaces++;
}
}

// only need to continue if we haven't gone past the end of the string
if ( start<theLine.length() )
{
// the next blank character is the end
for ( end=start ; end<theLine.length() && !Character.isSpaceChar( theLine.charAt( end ) ) ; end++ )
;

// we now have the word
result = theLine.substring( start, end );
}

return( result );
}
  
}

Answer 1

Following is the C language implementation of the given Java code. The code uses character array to process strings.

C CODE:

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

// Function to extract the word, from the given index.
const char * ExtractWord(char line[], int word, char result[]) {
   int i, j =0, ctr = 0;
   char wordList[10][10]; // Array to store each word separately.

   // For loop separates the line into separate words.
   for(i=0;i<=(strlen(line));i++) {
        // Assign NULL into wordList[], if NULL or spaces are encountered in the line.
        if(line[i]==' '||line[i]=='\0') {
            wordList[ctr][j]='\0';
            ctr++; // Scan next word
            j=0;    // index is set to 0 for a new word
        }
        else {
            wordList[ctr][j]=line[i];
            j++;
        }
   }
  
   // Check if index exceeds word limit.
   if(strlen( *wordList) < word) {
       printf("\nIndex is out of bound, exiting now.");
       exit(1);
   }
   // Extract the word from the given index from wordList[] and assign it to result.
    for(i=0;i < ctr;i++) {
       if(i == word) {
           strcpy(result, wordList[i]);
       }
   }
  
   return result;
}

// Main driver function
int main() {
    char line[100], result[20];
    int word, i, j;

    printf("\nEnter a line: ");
   scanf("%[^\n]",line);
   getchar(); // Get rid of newline char after scanf()
  
    printf("\nEnter the word index to extract: ");
    scanf(" %d", &word);

   // Invoke the function to extract the word
   strcpy(result, ExtractWord(line, word-1, result));
  
   printf("\nLine is: %s", line);
   printf("\nExtracted word at index %d is %s.", word, result);
  
   return 0;
}

OUTPUT:

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