Index: doc/binary.n
==================================================================
--- doc/binary.n
+++ doc/binary.n
@@ -760,10 +760,19 @@
 .CE
 .PP
 will return \fB2\fR with \fB01110\fR stored in \fIvar1\fR and
 \fB1000011100000101\fR stored in \fIvar2\fR.
 .RE
+.IP \fBC\fR 5
+This form is similar to \fBA\fR, except that it scans the data from start
+and terminates at the first null (C string semantics). For example,
+.RS
+.CS
+\fBbinary scan\fR "abc\e000efghi" C* var1
+.CE
+will return \fB1\fR with \fBabc\fR stored in \fIvar1\fR.
+.RE
 .IP \fBH\fR 5
 The data is turned into a string of \fIcount\fR hexadecimal digits in
 high-to-low order represented as a sequence of characters in the set
 .QW 0123456789abcdef .
 The data bytes are scanned in first to last

Index: generic/tclBinary.c
==================================================================
--- generic/tclBinary.c
+++ generic/tclBinary.c
@@ -1516,11 +1516,12 @@
 	if (!GetFormatSpec(&format, &cmd, &count, &flags)) {
 	    goto done;
 	}
 	switch (cmd) {
 	case 'a':
-	case 'A': {
+	case 'A':
+	case 'C': {
 	    unsigned char *src;
 
 	    if (arg >= objc) {
 		DeleteScanNumberCache(numberCachePtr);
 		goto badIndex;
@@ -1538,14 +1539,22 @@
 
 	    src = buffer + offset;
 	    size = count;
 
 	    /*
-	     * Trim trailing nulls and spaces, if necessary.
+	     * Apply C string semantics or trim trailing
+	     * nulls and spaces, if necessary.
 	     */
 
-	    if (cmd == 'A') {
+	    if (cmd == 'C') {
+		for (i = 0; i < size; i++) {
+		    if (src[i] == '\0') {
+			size = i;
+			break;
+		    }
+		}
+	    } else if (cmd == 'A') {
 		while (size > 0) {
 		    if (src[size - 1] != '\0' && src[size - 1] != ' ') {
 			break;
 		    }
 		    size--;

Index: tests/binary.test
==================================================================
--- tests/binary.test
+++ tests/binary.test
@@ -757,11 +757,20 @@
 test binary-21.12 {Tcl_BinaryObjCmd: scan} -setup {
     unset -nocomplain arg1
 } -body {
     list [binary scan "abc def \x00ghi  " A* arg1] $arg1
 } -result [list 1 "abc def \x00ghi"]
-
+test binary-21.13 {Tcl_BinaryObjCmd: scan} -setup {
+    unset -nocomplain arg1
+} -body {
+    list [binary scan "abc def \x00  " C* arg1] $arg1
+} -result {1 {abc def }}
+test binary-21.12 {Tcl_BinaryObjCmd: scan} -setup {
+    unset -nocomplain arg1
+} -body {
+    list [binary scan "abc def \x00ghi" C* arg1] $arg1
+} -result {1 {abc def }}
 test binary-22.1 {Tcl_BinaryObjCmd: scan} -returnCodes error -body {
     binary scan abc b
 } -result {not enough arguments for all format specifiers}
 test binary-22.2 {Tcl_BinaryObjCmd: scan} {
     unset -nocomplain arg1