update readme, fix a Makefile bug, change tex file name

Author: tangruize

README.md

@@ -15,7 +15,8 @@
 | 日期 | 主题 | 文件 |
 |------------|---------------------|-----------------------------------------------------------------------------------------------------------------------|
 | 2019-10-25 | 环境搭建和C语言入门 | [introduction.pdf](https://github.com/tangruize/programming-tutorial-2019/releases/download/slide_1/introduction.pdf) |
-| 2019-11-01 | 调试技巧, 函数和指针 | [function_array.pdf](https://github.com/tangruize/programming-tutorial-2019/releases/download/slide_2/function_array.pdf) |
+| 2019-11-01 | 调试技巧, 函数和数组 | [function_array.pdf](https://github.com/tangruize/programming-tutorial-2019/releases/download/slide_2/function_array.pdf) |
+| 2019-11-08 | 指针和动态内存 | [pointer_memory.pdf](https://github.com/tangruize/programming-tutorial-2019/releases/download/slide_3/pointer_memory.pdf) |
 
 ## [Tutorial](Tutorial)
 

Slides/2019-11-08_Pointer_Memory/Pointer_Memory.tex renamed to Slides/2019-11-08_Pointer_Memory/pointer_memory.tex

@@ -3,6 +3,7 @@ FLAGS = -file-line-error -synctex=1 -interaction=nonstopmode
 DIR ?=
 VIEWER ?=
 
+CMD_SUFFIX = &
 ifeq ($(DIR),)
 	AUTODIR = $(wildcard 201*)
 else
@@ -14,7 +15,6 @@ else
 			CMD_SUFFIX = ;
 		else
 			VIEWER = evince
-			CMD_SUFFIX = &
 		endif
 	endif
 endif
@@ -23,7 +23,7 @@ TEX = $(filter-out $(wildcard $(AUTODIR:%=%/preamble.tex)),$(wildcard $(AUTODIR:
 PDF = $(TEX:.tex=.pdf)
 
 slides: $(PDF)
-	@if which "$(VIEWER)" > /dev/null; then $(CMD_PREFIX) $(VIEWER) $(PDF) $(CMD_SUFFIX) fi
+	@if which "$(VIEWER)" &> /dev/null; then $(CMD_PREFIX) $(VIEWER) $(PDF) $(CMD_SUFFIX) fi
 
 $(PDF): %.pdf: %.tex
 	@cd $(dir $@) && latexmk -use-make -silent -xelatex $(FLAGS) $(notdir $(@:.pdf=.tex))