Add -help option

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

2 files changed, 23 insertions, 10 deletions

diff --git a/man/xcalc.man b/man/xcalc.man
index e286692..cb74d9b 100644
--- a/man/xcalc.man
+++ b/man/xcalc.man
@@ -43,8 +43,11 @@
 .SH NAME
 xcalc \- scientific calculator for X
 .SH SYNOPSIS
-.B xcalc
-[-stipple] [-rpn] [-\fItoolkitoption...\fP]
+.nf
+\fBxcalc\fP [\fB-stipple\fP] [\fB-rpn\fP] [-\fItoolkitoption...\fP]
+\fBxcalc -version\fP
+\fBxcalc -help\fP
+.fi
 .SH DESCRIPTION
 .I xcalc
 is a scientific calculator desktop accessory that can emulate a TI-30
@@ -52,7 +55,7 @@ or an HP-10C.
 .SH OPTIONS
 .PP
 \fIxcalc\fP accepts all of the standard toolkit command line options along
-with two additional options:
+with these additional options:
 .PP
 .TP 8
 .B \-stipple
@@ -66,6 +69,9 @@ This option indicates that Reverse Polish Notation should be used.  In this
 mode the calculator will look and behave like an HP-10C.  Without this flag,
 it will emulate a TI-30.
 .TP 8
+.B \-help
+This option indicates that \fIxcalc\fP should print its usage message and exit.
+.TP 8
 .B \-version
 This option indicates that \fIxcalc\fP should print its version and exit.
 .SH OPERATION
diff --git a/xcalc.c b/xcalc.c
index 34fef53..381edff 100644
--- a/xcalc.c
+++ b/xcalc.c
@@ -120,10 +120,13 @@ main(int argc, char **argv)
     /* Handle args that don't require opening a display */
     for (int n = 1; n < argc; n++) {
 	const char *argn = argv[n];
-	/* accept single or double dash for -version */
+	/* accept single or double dash for -help & -version */
 	if (argn[0] == '-' && argn[1] == '-') {
 	    argn++;
 	}
+	if (strcmp(argn, "-help") == 0) {
+            Syntax(1, argv);
+	}
 	if (strcmp(argn, "-version") == 0) {
 	    puts(PACKAGE_STRING);
 	    exit(0);
@@ -325,17 +328,21 @@ void Quit(void)
  */
 static void Syntax(int argc, char **argv)
 {
-    fprintf(stderr, "%s: unknown options:", argv[0]);
-    for (int i = 1; i <argc; i++)
-	fprintf(stderr, " %s", argv[i]);
-    fprintf(stderr, "\n\n");
+    if (argc > 1) {
+        fprintf(stderr, "%s: unknown options:", argv[0]);
+        for (int i = 1; i <argc; i++)
+            fprintf(stderr, " %s", argv[i]);
+        fprintf(stderr, "\n\n");
+    }
     fprintf(stderr, "Usage:  %s", argv[0]);
     for (Cardinal i = 0; i < XtNumber(Options); i++)
 	fprintf(stderr, " [%s]", Options[i].option);
     fprintf(stderr, "\n");
+    fprintf(stderr, "        %s -help\n", argv[0]);
     fprintf(stderr, "        %s -version\n", argv[0]);
-    XtDestroyApplicationContext(xtcontext);
-    exit(1);
+    if (xtcontext != NULL)
+        XtDestroyApplicationContext(xtcontext);
+    exit((argc > 1) ? 1 : 0);
 }
 
 /*