代写PHYS 105、代做Large Programs、代写C/C++程序、代做C/C++设计

日期：2018-12-04 10:16

PHYS 105 Lecture 14: Large Programs and

Makefiles

Sean Fleming

Dept. of Physics

University of Arizona

November 27 & 28

Last time

I Orbital Motion

This time

I Large Programs

I Makefiles

Large Programs

As you may have noticed, our programs are growing ever

larger. This becomes a problem if you want an individual file to

be readable. In general, it is good coding philosophy to break a

large file into smaller pieces that all do a self-contained

operation. This is the philosophy we will take in breaking apart

some of our larger programs.

Breaking apart gaussian.c

Today, we will break apart the gaussian.c program that we

wrote way back when. Feel free to copy/paste into a new file,

but I will be writing the code from scratch.

Our strategy will be to put the gaussian function, previously

written just below the main(), into its own file.

Header files

The way you link c-files together is through “header” files.

These files contain the prototypes of the functions found in an

identically named c-file. For this program, we will create a

header called “function.h” for the c-file called “function.c”.

function.h

This file, called “function.h” contains the prototype and library

links used in the code with the same name but a “.c” suffix.

//Function prototypes are put in headers

//As well as inclusions of libraries

#include <math.h>

float gaussian(float x);

function.c

The function itself is in a c-file.

//Link back to the header

#include "function.h"

float gaussian(float x){

return exp(-x*x);

}

gauss_main.c

The entire main is in its own file.

//Tom McClintock

//PHYS 105

//to compile: $make

//to run: $gaussian.exe

#include <stdio.h>

//Include your own header files here!

#include "function.h"

int main()

{

int i, N = 20;

float xLo = -5, xHi = 5,x = xLo, y;

float step = (xHi-xLo)/N;

for(i = 0; i < N; i++){

y = gaussian(x);

printf("x = %f y = %e\n",x,y);

x = x + step; //increment x

}

}

Superglue: the Makefile

As you may have noticed, the compilation instructions are

different. For programs with many c-files and headers, it is a

pain to compile at the command line. For this reason, we make

a Makefile. A Makefile is like a recipe: it contains the

instructions on how to make our executable.

Makefile

#Name the executable

EXEC = gaussian.exe

#List all of the "objects" you will compile

OBJS = gauss_main.o function.o

#Name your c-ccompiler

CC = gcc

#Link to any libraries

OFLAGS = -lm

.SUFFIXES:.c.o

%.o: %.c

$(CC) -c $< -o $@

$(EXEC): $(OBJS)

$(CC) $(OBJS) -o $(EXEC) $(OFLAGS)

rm $(OBJS)

Compiling and running

To compile a program with a Makefile all you have to do is type

“make”. To run you just type the name of the executable.

Final Project

I Due on “final” date: Tu. Dec. 11, W. Dec. 12

I In class assignment: Work on your final project.

Next time

I Python programs

Work on your final project!

HW 7 - Harmonic Motion due in one week

Simulate a ball hanging from the ceiling by a spring, and include

air resistance. The force for this would look like the following:

Fy = mg bv 2

vy

v

ky

where F~ always points in the y direction. Here, y is the

displacement from the origin. Simulate this with initial

conditions y(0) = +1.0 and v(0) = ?1.0, with constants of

b = 0.1 and k = 20.0. You can quickly write this homework by

modifying your projectile motion program.