Lab 5. Functions & make
PROBLEM:
- (1) Write a function named compute that finds both the area and the circumference of a circle.
Your function must use pointer notation (the address operator “&” and the indirection
operator “*”), and will be a separate file (compute.c) from the other code (lab5.c).
- (2) You are required to create a working makefile.
- (3) You must edit lab5.c to add your name at the top, and add you name at about line 35
fprintf(data_out, “\nYour name here. Lab 5. \n\n”);
The function prototype is:
/* Function to compute the area and the circumference */
/*ofacircle */
void compute(double radius, double *area, double *cir);
You will need the file lab5.c as your main/driver program for the function. This main program will set things up, read the values from the file, and print the output sentences.
You will also need lab5.h and lab5.dat.
THE FORMULAS (in algebraic notation)(must be translated to C notation): (1) area of a circle (2) circumference of a circle
a=PI*radius2 c=2*PI*radius
TO GET THE FILES YOU NEED:
First move to your class folder by typing: cd csc60
The following command will create a directory named lab5 and put all the needed files into it below your csc60 directory.
Type: cp -R /gaia/home/faculty/bielr/files_csc60/lab5 .
Spaces needed: (1) After the cp ↑ Don’t miss the space & dot.
(2) After the -R
(3) After the directory name at the end & before the dot.
After the files are in your account and you are still in csc60, you need to type: chmod 755 lab5 This will give permissions to the directory.
Next move into lab5 directory (cd lab5), and type: chmod 644 lab5*
This will give permissions to the files.
Your new lab5 directory should now contain: lab5.c, lab5.h, lab5.dat
INPUT/OUTPUT DESCRIPTION:
The input is a list of varying length of type double values in the file lab5.dat. will have one value for the radius.
The output is a chart showing the radius, area, and circumference of a circle.
Each record (or line)
CSC60. Lab 5. Functions & make Page 2 of 5.
DEFINED OUTPUT APPEARANCE:
Print statements are included in the main program, and require no changes, except your name. Your name here. Lab 5.
Radius Area Circumference -------- -------- ---------------
3.70 43.01 23.25 6.80 145.27 42.73
ONLY the first two lines are shown here. You should validate the correctness of the other lines.
ALGORITHM DEVELOPMENT – Pseudo code: /*————————————————————————-*/ main /*mainisgiventoyouaslab5.c */
Open the data file and check for error on open. Open the output file and check for error on open. Print headers.
while ( good data reading(fscanf) a radius )
Call compute
Print the radius, area, and circumference. Close the files.
/*————————————————————————-*/ /* This code, compute.c, will reside in a separate file */ /* from the main function */ /* Function to compute the area and the circumference */ /* of a circle */ /* Remember: #include “lab5.h” */
void compute(double radius, double *area, double *cir)
Calculate the area
Calculate the circumference Return
/*————————————————————————-*/
REMINDERS:
- Remember to put your name and Lab 5 in the comment header and in the output.
- Remember the operator for multiplication is the asterisk (*).
- Since we are already including math.h, use M_PI for the value of PI.
- You should examine the data file and confirm the correctness of the answer produced by your
program.
- Changes: lab5.c to add your name; create compute.c in separate file; create a makefile
- You will also need to add -lm on the line that does the gcc in the makefile.
- The Output is going to the file lab5.out
CSC60. Lab 5. Functions & make Page 3 of 5.
CREATING A MAKE FILE: Use the slides 13-15 of 5-UNIX as a reference. Also pasted here. The Dependency Chart of Lab5 program:
lab5.o
lab5.c lab5.h
compute.o
compute.c lab5.h
lab5
The first line should be a comment with your name.
Next: use a name like lab5, followed by the *.o files and the *.h file
Next: one or two tabs followed by the *.o files and the rename of the executable
You will need to add -lm on the line that does the gcc in the makefile. Next: the *.o file name, followed by a colon,
followed by the *.c file and the *.h name Next: compile without linking the .c file Separate your Rules with empty lines.
PREPARE YOUR FILE FOR GRADING:
When all is well and correct,
Type: script StudentName_lab5.txt [Script will keep a log of your session.] Type: touch lab5.h to force a recompilation
Type: make to compile the code
Type: lab5 to run the program to show the output of the program
(or whatever name you used for the executable) Type: cat lab5.out to see the output of your program
Type: exit to leave the script session
