pdf for printing - Image Processing and Analysis Group

Compiling a more complicated
C++ program and library
Project consists of 5 files:
1. utility.h -- header file defining the specifications of the utility code
2. Utility.cpp – actual code for the utility code
3. Print.h – header file for the printing code
4. print.cpp – implementation of the printing code
5. Main.cpp -- main program that uses code in utility.cpp and
print.cpp
Plan:
1. Create a library containing the code in utility.cpp and readwrite.cpp
2. Link the library with the object file main.o to create the executable
print.h
print.h and print.cpp
#include
void printnumber(float t);
print.cpp
#inlcude “print.h”
void printnumber(float t)
{
printf(”The number is %5.2f\n”,t);
}
Compling and Linking
Method 1 – no libaries
g++ -c utility.c produces utility.o
g++ -c print.c produces print.o
g++ -c main.c produces main.o
g++ -o main main.o utility.o print.o –lm
This yields the final executable main
Note that the following one-step procedure is also possible but only
useful for really small projects:
g++ -o main main.cpp utility.cpp print.cpp –lm
Utility.h
Utility.h and Utility.cpp
#include
float deg2rad(float t);
Utility.cpp
#include “utility.h”
float deg2rad(float t)
{
return t*M_PI/180.0;
}
main.cpp
#include “print.h”
#include “utility.h”
#include “math.h”
Main.cpp
int main (int argc,char **argv)
{
float t=40.0;
float trad=deg2rad(t);
float costrad=cos(trad);
printnumber(costrad);
}
Compling and Linking
Method 2 – static library method
g++ -c utility.c produces utility.o
g++ -c print.c produces print.o
ar -cr libutil.a print.o utility.o produces libutil.a
(a ranlib step may also be needed)
g++ -c main.c produces main.o
g++ -o main -lutil –lm
This yields the final executable main by linking it with the library libutil.a and the
math library libm.so. The size of main is approximately equal to
Size(main,o) + size(libutil.a) + overhead
The executable main will run just fine even if libutil.a is deleted.