Make GMP optional for the examples

example/Makefile

@@ -1,18 +1,24 @@
 CC=cc -std=c99
 CFLAGS=-Wall -W -pedantic -Wshadow -Wpointer-arith -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wswitch-default -Wswitch-enum -Wcast-align -Wpointer-arith -Wbad-function-cast -Wstrict-overflow=5 -Wstrict-prototypes -Winline -Wundef -Wnested-externs -Wcast-qual -Wshadow -Wunreachable-code -Wlogical-op -Wstrict-aliasing=2 -Wredundant-decls -Wold-style-definition -Wno-unused-function
-CPPFLAGS=-I..
-LDFLAGS=-pthread -lgmp
+GMP_DIR=
+CPPFLAGS=-I.. -I$(GMP_DIR)/include
+LDFLAGS=-pthread -L$(GMP_DIR)/lib
 RM=rm -f
 
 .SUFFIXES: .c .exe
 
 .c.exe:
-	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) `cat config` $< -o $@
 
-all:
+all: config
 	$(MAKE) `ls ex-*.c|sed -e 's/\.c/\.exe/g'`
 
+config:
+	printf "#include <gmp.h>\nint main(void){mpz_t z; mpz_init(z); return 0;}\n" > config-test.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) -lgmp config-test.c -o config-test.exe 2> /dev/null && echo "-DHAVE_GMP=1 -lgmp" > config || echo "-DHAVE_GMP=0" > config
+	$(RM) config-test.*
+
 clean:
-	$(RM) *.exe *.s *~ *.o ./a.dat
+	$(RM) *.exe *.s *~ *.o ./a.dat config
 
 

example/ex-array04.c

@@ -1,3 +1,5 @@
+#if HAVE_GMP
+
 #include <gmp.h>
 
 #include "m-array.h"
@@ -35,3 +37,8 @@ int main(void)
   array_mpz_clear(a);
   mpz_clear(z);
 }
+
+#else
+// Nothing to do
+int main(void) { return 0; }
+#endif

example/ex-multi02.c

@@ -1,3 +1,5 @@
+#if HAVE_GMP
+
 #include <stdio.h>
 #include <gmp.h>
 
@@ -61,3 +63,8 @@ int main(void)
         }
     } /* All variables are automatically cleared beyond this point */
 }
+
+#else
+// Nothing to do
+int main(void) { return 0; }
+#endif