initial checkin

2 files changed, 67 insertions, 0 deletions

diff --git a/test1/Makefile b/test1/Makefile
new file mode 100644
index 0000000..d9854f1
--- /dev/null
+++ b/test1/Makefile
@@ -0,0 +1,10 @@
+CFLAGS=-std=c99 -Wall -Werror
+
+all: parse
+
+test: parse
+	printf "9-5+2" | ./parse
+	printf "9-5+2+" | ./parse
+
+clean:
+	-rm -f parse
diff --git a/test1/parse.c b/test1/parse.c
new file mode 100644
index 0000000..1b92490
--- /dev/null
+++ b/test1/parse.c
@@ -0,0 +1,57 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+int c;
+
+void match( char t )
+{
+	if( c == t ) {
+		c = getc( stdin );
+	} else {
+		fprintf( stderr, "\nERR: expecting '%c', but got '%c'\n", t, c );
+		exit( 1 );
+	}
+}
+
+void term( void )
+{
+	if( isdigit( c ) ) {
+		int t = c;
+		match( c );
+		putchar( t );
+	} else {
+		fprintf( stderr, "\nERR: expecting digit, but got '%c'\n", c );
+		exit( 1 );
+	}
+}
+
+void rest( void )
+{
+	if( c == '+' ) {
+		match( '+' ); term( ); putchar( '+' ); rest( );
+	} else if( c == '-' ) {
+		match( '-' ); term( ); putchar( '-' ); rest( );
+	}
+}
+
+void expr( void )
+{
+	term( ); rest( );
+}
+
+int main( void )
+{
+	c = getc( stdin );
+
+	expr( );
+
+	if( ( c = getc( stdin ) ) != EOF ) {
+		fprintf( stderr, "\nERR: superfluos input found\n" );
+		exit( 1 );
+	}
+
+	puts( "" );
+
+	exit( 0 );
+}