Help needed in c program threads linux ! Thanx

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Exercise 4.31.40: (parsestring.c) Write a C program that does the fol- lowing until EOF: i) reads a line from standard input, including an empty line, with getline, ii) tokenizes the line based on spaces and tabs, iii) builds a NULL-terminated array of character arrays (pointers), no larger than necessary, to store a pointer to each token of the line, iv) write each token to standard output from that array of character pointers, and v) frees the array of character pointers. For instance, if the input line is one two three four, the structure built is char* parsedstring[] char** parsedstring 1100 11100 1000 1004 1008 1014 NULL 4 char* line 1004 1008 1000 O''n''e' '10't''W' 1000 ' 10' 'n' 'r' 1014 10'''''''' 'e' 'e' ' and the output is: 1 :one: 2 :two: 3 :three: 4 :four: The following are some sample, non-exhaustive test cases. Your program is expected to produce identical output. Do not prompt for input. 1 $ ./a.out 2 one two three four 3 :one: 4 :two: 5 :three: 6 :four: 7 apple orange pear lemon lime 8 : apple: 9 : orange: 10 :pear: 11 :lemon: 12 :lime: 13 14 -a -b -c -d -e -f -h 15 :-a: 16 :-b: 17 :-c: 18 :-d: 19 :-e: 20 :-f: 21 :-h: 22 4D 23 $ 24 $ cat input.txt 25 one two three four 26 apple orange pear lemon lime 28 -a -b -c -d -e -f -h 29 $ 30 $ ./a.out