CODEWITHSUNDEEP
c
Yamaha32088
Yamaha32088

Reputation: 4163

Customize the make command

I want to know how instead of running

gcc -std=c99 foo.c -o foo -lcs50

I can just run 

make foo

The problem is that when I try it with just the make command it says 

cc     foo.c   -o foo
Undefined symbols for architecture x86_64:
  "_GetString", referenced from:
      _main in crypto-6PNyQP.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [crypto] Error 1

But when I include the other flags in using the gcc command it works just fine. I am taking an online class and they are able to just type in make foo and their output will be

jharvard@appliance (~/Desktop): make foo
gcc -ggdb -std=c99 -Wall -Werror    foo.c  -lcrypt -lcs50 -lm -o foo
jharvard@appliance (~/Desktop):

I have searched google for a while now trying to find the answer to this question but still no luck.

Upvotes: 1

Views: 302

Answers (2)

Jonathan Leffler
Jonathan Leffler

Reputation: 754860

Using GNU make:

make CFLAGS=-std=c99 LDLIBS=-lcs50 foo

Or put those macros into a 2-line makefile:

CFLAGS = -std=c99
LDLIBS = -lcs50

For the more complex options you showed in your last example:

CFLAGS = -ggdb -std=c99 -Wall -Werror
LDLIBS = -lcrypt -lcs50 -lm

With a makefile like this, you can build any program xyz from a single source file xyz.c using just:

make xyz

When you need to create programs from multiple source files, you'll need a more complex makefile.

Upvotes: 2

brunobeltran0
brunobeltran0

Reputation: 74

There is a discussion board (joinable through google groups) that specializes in answering question pertaining to configuration of the CS50 appliance, which is what I assume you are running since you are taking Harvard's CS50 online.

CS50 in a Box (the appliance) should be configured so that when you type make, the 'right' thing happens during the first few homework assignments, so that you don't have to worry about the specifics of compilation right away.

However, if it seems to not be working, you could post a question to the group I mentioned above, "cs50-discuss". If you are (unadvisedly) using your own setup instead of the appliance, you could simply search for how to make a 'Makefile', the text file which is read by the program 'make' when you run it. Having a Makefile will allow you to ensure that the command that you want to be run is correctly called when you invoke 'make'.

Upvotes: 0

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