In the string tutorial: Added try...finally and moved a small code snippet back to the .rst file.

docs/examples/tutorial/string/assignment.pyx

-from libc.stdlib cimport free
-from c_func cimport c_call_returning_a_c_string
-
-
-def main():
-    cdef char* c_string = c_call_returning_a_c_string()
-    cdef bytes py_string = c_string
-
-    # A type cast to `object` or `bytes` will do the same thing:
-    py_string = <bytes> c_string
-
-    free(c_string)

docs/examples/tutorial/string/c_func.pyx

@@ -7,12 +7,16 @@ cdef Py_ssize_t n = strlen(hello_world)
 
 cdef char* c_call_returning_a_c_string():
     cdef char* c_string = <char *> malloc((n + 1) * sizeof(char))
+    if not c_string:
+        raise MemoryError()
     strcpy(c_string, hello_world)
     return c_string
 
 
 cdef void get_a_c_string(char** c_string_ptr, Py_ssize_t *length):
     c_string_ptr[0] = <char *> malloc((n + 1) * sizeof(char))
+    if not c_string_ptr[0]:
+        raise MemoryError()
 
     strcpy(c_string_ptr[0], hello_world)
     length[0] = n

docs/examples/tutorial/string/slicing_c_string.pyx

@@ -9,8 +9,7 @@ def main():
     # get pointer and length from a C function
     get_a_c_string(&c_string, &length)
 
-    py_bytes_string = c_string[:length]
-
+    try:
+        py_bytes_string = c_string[:length]  # Performs a copy of the data
+    finally:
         free(c_string)
-    print(py_bytes_string)  # py_bytes_string is still available
-

docs/src/tutorial/strings.rst

@@ -107,7 +107,7 @@ within a well defined context.
 Passing byte strings
 --------------------
 
-we have a dummy C functions declared in
+we have dummy C functions declared in
 a file called :file:`c_func.pyx` that we are going to reuse throughout this tutorial:
 
 .. literalinclude:: ../../examples/tutorial/string/c_func.pyx
@@ -119,9 +119,16 @@ We make a corresponding :file:`c_func.pxd` to be able to cimport those functions
 It is very easy to pass byte strings between C code and Python.
 When receiving a byte string from a C library, you can let Cython
 convert it into a Python byte string by simply assigning it to a
-Python variable:
+Python variable::
 
-.. literalinclude:: ../../examples/tutorial/string/assignment.pyx
+    from c_func cimport c_call_returning_a_c_string
+
+    cdef char* c_string = c_call_returning_a_c_string()
+    cdef bytes py_string = c_string
+
+A type cast to :obj:`object` or :obj:`bytes` will do the same thing::
+
+    py_string = <bytes> c_string
 
 This creates a Python byte string object that holds a copy of the
 original C string.  It can be safely passed around in Python code, and