Makefile variable to c program - c

Question

Hello i need help with makefile variables.
make build //(compiler server)
make run PORT=something //(run server on port something)
I need save this variable and post to the server.c and client.c Here is my Makefile
SERVER=server
CLIENT=client
FILES=src/server.c src/client.c
CFLAGS=-std=gnu99 -Wall -Wextra -Werror -pedantic
CC=gcc
build:
$(CC) $(CFLAGS) -o $(SERVER) src/server.c
$(CC) $(CFLAGS) -o $(CLIENT) src/client.c
run:
./server
clean:
$(RM) *.o src/$(CLIENT) src/$(SERVER

Answer 1

A plausible outline for a compile-time decision about port number might be:
SERVER = server
CLIENT = client
SERVER.c = src/server.c
CLIENT.c = src/client.c
CFLAGS = -std=gnu99 -Wall -Wextra -Werror -pedantic
PORT = 9823
DFLAGS = -DPORT=$(PORT)
CC = gcc
all: build
build: $(CLIENT) $(SERVER)
$(CLIENT): $(CLIENT.c)
$(CC) $(CFLAGS) $(DFLAGS) -o $(CLIENT) $(CLIENT.c)
$(SERVER): $(SERVER.c)
$(CC) $(CFLAGS) $(DFLAGS) -o $(SERVER) $(SERVER.c)
run: $(CLIENT) $(SERVER)
./$(SERVER)
clean:
$(RM) *.o $(CLIENT) $(SERVER)
The code for the client and the server contains code such as this, preferably in a common header:
#ifndef PORT
#define PORT 1234
#endif
and references PORT where the port number is needed.
If it is strictly a run-time decision, then maybe you use:
SERVER = server
CLIENT = client
SERVER.c = src/server.c
CLIENT.c = src/client.c
CFLAGS = -std=gnu99 -Wall -Wextra -Werror -pedantic
PORT = 9823
CC = gcc
all: build
build: $(CLIENT) $(SERVER)
$(CLIENT): $(CLIENT.c)
$(CC) $(CFLAGS) -o $(CLIENT) $(CLIENT.c)
$(SERVER): $(SERVER.c)
$(CC) $(CFLAGS) -o $(SERVER) $(SERVER.c)
run: $(CLIENT) $(SERVER)
./$(SERVER) -p $(PORT)
clean:
$(RM) *.o $(CLIENT) $(SERVER)
You'd also need to tell the client to connect to the given port number, of course. You should still have a default port number that is shared by both client and server in some common header.
You might use a hybrid of these solutions, where you define the default port number in the build process and use it in the run rule too.