LAB 7 (June 29/July 4) Structures, Stream I/O, Self-referential structures (Linked list) in C

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1 LAB 7 (June 29/July 4) Structures, Stream I/O, Self-referential structures (Linked list) in C Due: July 9 (Sun) 11:59 pm 1. Prblem A Subject: Structure declaratin, initializatin and assignment. Structure and functins. Array f structures. Implementatin 1. Dwnlad file lab7a.c. Lk at the existing cde, and then cmplete the prgram by fllwing the cmments. Observe hw a structure type is defined hw a struct variable is declared and initialized at declaratin hw a struct variable s member values are set after declaratin that, when a struct variable is assigned/cpied t anther struct variable the values f the members are cpied the tw structures are independent. Changing members f ne struct des nt affect the ther. Hwever, if the structure has pinter member, then after cpy, bth pinters pint t the same pintee. hw an array f structures is declared, initialized at declaratin, and set after declaratin that functin prcessstruct() des nt wrk as expected. 2. Fix the definitin f functin prcessstruct() as well as its functin call, s that argument structure can be updated crrectly. Sample Inputs/Outputs: (The hexadecimal memry address wuld be different frm here) red 326 % a.ut simple struct a: b: b.int2: 555 a: b: struct with pinter member xx: 5 0x7fffa2b65b1c 100 yy: 5 0x7fffa2b65b1c 100 xx: 5 0x7fffa2b65b1c yy: 5 0x7fffa2b65b1c struct with array member [ ] struct and functin struct a befre prcess: struct a after prcess:

2 array f structs arr[0]: 1 2 arr[1]: 3 4 arr[2]: 5 6 red 327 % Submissin Submit yur prgram using submit 2031 lab7 lab7a.c 2. Prblem B Subject: Standard I/O vs. Stream I/O. Implementatin Cpy file lab7a.c t lab7b.c, and then replace all the Standard I/O functins (what are they?) with their crrespnding Stream (general) versin I/O functins. Sample Inputs/Outputs: Exactly the same as abve. Submissin Submit yur prgram using submit 2031 lab7 lab7b.c After submissin, as an additinal practice, cmment ut the statement which riginally uses scanf(). Cmpile and run with a.ut > ut.txt Observe that nthing is printed n the screen, as all the utputs t stdut are redirected t file ut.txt. a text file ut.txt is created, with all the utputs written in. (Check the cntent f ut.txt t cnfirm that all the utputs are written t the file.) Then, mdify the last I/O statement (which prints structure array in lp) such that it prints t stderr. Cmpile and run with a.ut > ut2.txt. If dne crrectly, then yu will bserve that the utputs sent t stderr are nt redirected t the file, and are still printed n the screen. a text file ut2.txt is created, with all the utputs sent t stdut written in it, except the utputs that are sent t stderr. (Check the cntent f ut2.txt t cnfirm.) 3. Prblem C Subject: Array f structures. Stream I/O, Specificatin Write an ANSI-C prgram that first reads input strings line by line frm a disk file, and stres the inputs in an array f structures. The prgram then reads frm the array f structures, refrmat the infrmatin and writes (appends) them int the same disk file. 2

3 Implementatin Dwnlad file lab7c.c and start frm there. Define a structure peple, which cntains the fllwing fields: name f type char [] r char * int age flat wage Open a data file data.txt using FILE IO in C, and read line by line frm the file using stream IO (what are they?). Stre each line f infrmatin int an array f struct peple. assume that there are n mre than 30 lines f recrds in the disk file. assume that each line f the disk file cntains n mre than 50 characters, and each line cntains a string, an integer, a flating pint number separated by spaces., which represents the name, age, wage infrmatin f a peple respectively. read the data file line by line, and stre the string, int and flat in each line int arr, which is an array f struct peple. Specifically, the structure in arr[i] gets the string, int and flat frm line i f the file, fr its name, age and wage members respectively. Fr example, the structure in arr[0] gets the name, age, and wage fr its members frm the infrmatin in the first line f the data file, arr[1] gets the values fr its members frm the infrmatin in the secnd line f the file and s n. after reading, display the structure array n the stdut finally, read all the data frm the array f structures, mdify infrmatin read frm each structure in such a way that age is increased by 10, wage has 50% increase and has 3 digits after decimal pints. Then write (append) the refrmatted infrmatin int the same disk file. Sample Inputs/Outputs: red 329 % cat data0.txt Lisa Zha Eric Jeasn red 330 % a.ut arr[0]: Lisa arr[1]: Zha arr[2]: Eric arr[3]: Jeasn red 331 % red 332 % cat data0.txt Lisa Zha Eric Jeasn Lisa Zha Eric Jeasn Submissin Submit yur prgram using submit 2031 lab7 lab7c.c 3

4 4. Array f structures, Stream/File IO, Linked list Backgrund: Singly Linked list Skip this sectin if yu are familiar with linked list and its basic data structure in C A linked list cnsists f a chain f structures (called ndes), with each nde cntaining a pinter (in Java this is a reference ) t the next nde in the chain. Nte that the last nde in the list cntains a NULL pinter. T build up a linked list, the first thing we need is a structure that represents a single nde in the list. Fr simplicity, let s assume that a nde cntains nly ne integer data field. S a nde struct cntains nthing but an integer (the nde s data) plus a pinter t the next nde in the list. Here is what ur nde structures lk like in C: struct nde { int data; struct nde * next; }; Nte that the next field has type struct nde *, which means it can stre the address f anther nde structure (which is, f curse, f the same type f this nde). Nw that we have the nde structure declared, we need a way t keep track f where the list begins. In ther wrds, we need a variable that always pints t the first nde in the list, which serves as ur nly access pint t the whle list. Let s name the variable head: struct nde * head; Nte that when the list is empty, head is NULL. Create and insert a new nde int the list In general, creating and inserting a new nde t the list requires three steps: 1. Allcate memry fr the nde (hw?) 2. Stre data in the nde 3. Insert the nde int the list, which invlves finding the prper place fr the new nde, and setting the pinters f the new nde and its neighbrs prperly. 4

5 Remve a nde frm the list Deleting a nde als invlves three steps 1. Lcate the nde t be deleted 2. Alter the previus nde s that it bypasses the deleted nde 3. Free the space ccupied by the deleted nde. 4.0 Prblem D0 Subject: Linked list implementatin n stack (in main) Implementatin: Dwnlad file lab7d0.c, lk at the cde and play with it. Observe that this implementatin, which is nt very practical, creates ndes and link them directly. 4.1 Prblem D1 Subject Linked list implementatin n stack (in functin) Implementatin: Dwnlad file lab7d1.c, which mves the repeated implementatin f insertin int a functin addbegining(). Cmpile and run the prgram, what yu get? Explain why lab7d0.c wrks but nt this versin. Hint: remember setarr2.c which yu just did in lab 6? Write yur answer n the file, and submit using submit 2031 lab7 lab7d1.c. 4.2 Prblem D2 Subject Linked list implementatin n heap. Implementatin: Fix the implementatin f addbegining()in lab7d1.c, name the new prgram lab7d2.c Sample utput: red 330 % a.ut red 331 % Submissin: Submit using submit 2031 lab7 lab7d2.c. 5

6 4.3 Prblem D3 Subject: Stream IO + Structures + Array f structures + Linked list Specificatin Based n the prir practice, implement a full-fledge Linked list data structure in C. Yu are prvided with a partially implemented prgram lab7d3.c, and a data file data.txt. Implementatin Dwnlad the partially implemented file lab7d3.c, study the existing cde there, and then implement the fllwing functinalities. Open a data file data.txt using FILE IO in C. The file cntains lines f integers, each line cntains exactly tw integers. Read the data file line by line, and stre the tw integers in each line int arr, which is an array f struct integers. the structure integers cntains tw data members. the structure in arr[i] gets the tw values fr its data members frm the tw integers in the i th line f the file. Fr example, the structure in arr[0] gets the tw values fr its members frm the tw integers in the first line f the file, arr[1] gets the tw values fr its members frm the tw integers in the secnd line f the file, and s n. Build the linked list (pinted by head) by reading in each structure in the array, adding up the tw int fields and then inserting the sum value int the linked list. Implement r cmplete the fllwing functins. int len (), which returns the length f the list. int search(int key) which searches the list fr nde with data key. vid insert(int d), which inserts at the end f the list a new nde with data d vid insertafter(int d, int index), which inserts int the list a new nde with data d,after the n th nde. (The first nde is cnsidered the 0 th nde.) Assume that index is valid in the range [0,len()-1]. vid delete(int d), which remves the nde in the list that has data value d. If the list is empty, write errr message t stderr and exits. Assume that if the list is nt empty, then all the ndes in list have distinct data, and the nde with data d exists in the list. Dn t frget t free the memry space ccupied by the deleted nde. Sample Inputs/Outputs: If implemented crrectly, the prgram shuld give the fllwing interesting utputs: 6

7 red 314 % cat data.txt red 315 % a.ut arr[0]: 3 4 arr[1]: 1 2 arr[2]: 3 2 arr[3]: 6 0 arr[4]: 3 5 arr[5]: 4 5 arr[6]: 2 0 arr[7]: 0 0 arr[8]: 1 0 insert 7: (0) 7 insert 3: (1) 7 3 insert 5: (2) insert 6: (3) insert 8: (4) insert 9: (5) insert 2: (6) insert 0: (7) insert 1: (8) remve 0: (9) remve 1: (8) remve 2: (7) remve 3: (6) remve 5: (5) remve 6: (4) remve 7: (3) 8 9 remve 8: (2) 9 remve 9: (1) insert 7: (0) 7 insert 3: (1) 7 3 insert 5: (2) insert 6: (3) insert 8: (4) insert 9: (5) insert 2: (6) insert 0: (7) insert 1: (8) insert -4 after index 2: (9) insert -6 after index 0: (10) insert -8 after index 6: (11) search 5... fund search nt fund search 9... fund search nt fund search 0... fund search fund red 316 % Number in () indicates the current length f the list (befre insertin/deletin) 7

8 Nte: main functin des nt cver all the cases. Yu may want t test ther cases. Submissin: Submit yur prgram using submit 2031 lab7 lab7d3.c.c In summary, fr this lab yu shuld submit lab7a.c lab7b.c lab7c.c lab7d1.c lab7d2.c lab7d3.c Cmmn Ntes All submitted files shuld cntain the fllwing header: /*************************************** * CSE2031 Lab 7 * * Filename: Name f file * * Authr: Last name, first name * * Yur address * * eecs_num: Yur eecs lgin username * ****************************************/ In additin, all prgrams shuld fllw the fllwing guidelines: Include the stdi.h library in the header f yur.c files. Use /* */ t cmment yur prgram. Yu are nt encuraged t use // Give a return type int fr main(), and return 0 at the end f main() 8