STL map operator[] not const

STL里Map的Operator[]和其它的Container不太一样。因为Map的Operator[]可以提供这种操作: map testMap; testMap[“a”] = “b”; 所以Map的Operator[]返回的是T&，而不是const T& 如果需要得到const reference,可以这样: map testMap; const string& constMember = testMap.find(“a”)->second;

UnitTest框架GoogleTest

回到C++下，随着代码量增加，遇到维护问题了。找到一个Google的UnitTest框架，GoogleTest 有很详细的Sample，推荐一下 :] 编译的时候需要先编译出libgtest.a和gtest_main.o，自己的testXX.cpp文件需要和ligtest.a, gtest_main.o链接。 $g++ testXX.cpp path/to/gtest_main.o -Lpath/to/libgtest.a -lgtest -o testXX

Project-Specific Vim Configuration

Usually, we have our own vim configuration in the file ~/.vimrc What if we want one for our project? For example, we are working on certain project which needs to read in a tags file. Well, here is a possible solution. You put a line at then end of your ~/.vimrc file source ./.project.vim Then […]

tail -n

Quite useful trick, when you want to get rid of the first certain lines of the output/file. $tail -n +2 tail prints out the result starts from the 2nd line. When you use the “find” command to generate a file list under certain folder, this is quite easy to eliminate the folder path at the […]

Draw ROC Curve

A piece of fairly simple Matlab script to draw the ROC Curve from an array of scores and an array of labels. function [Tps, Fps] = ROC(scores, labels) %% Sort Labels and Scores by Scores sl = [scores; labels]; [d1 d2] = sort(sl(1,:)); sorted_sl = sl(:,d2); s_scores = sorted_sl(1,:); s_labels = round(sorted_sl(2,:)); %% Constants counts […]

log和logf

用C/C++处理数据的时候，如果数值比较大就得注意数据类型。比如这个log函数的问题。 log接受double类型的参数，而logf接受float类型。比如这段代码: #include #include int main() { double x = 4.4e52; printf(“log(%lf) = %f\n”, x, log(x)); printf(“log(%lf) = %f\n”, x, logf(x)); return 0; } linux/gcc下的输出是 log(43999999999999999701721741671911630964315171445538816.000000) = 121.216029 log(43999999999999999701721741671911630964315171445538816.000000) = inf

龙年快乐

Happy Chinese New Year! 今天这边下雪了，到这里之后见到的第一场雪。上午出去走了走，胡乱的拍了几张照片。刚过来这边，每每看到有人在给动物喂食就感觉很有爱，尤其是在这样的大雪天。就要到龙年了，希望朋友们平安快乐，希望家里一切都好。

vimGdb

又回到了用VIM的状态。刚装起来了vimGdb，vim的各种gdb插件还是这个比较顺手。唯一的不足之处是vimGdb需要给源码打一个Patch。 vim最新的稳定版本是7.3，对应的vimGdb在这里 larrupingpig/vimgdb-for-vim7.3 下面的说明比较清楚了，需要注意的是vim的源码必须是 vim-7.3.tar.bz2 这个包，如果是从最新的库里checkout的代码会和patch不匹配。比如在~/Temp下有 vim-7.3.tar.bz2 vimgdb-for-vim7.3.tar.gz 解压 $tar xvf ./vim-7.3.tar.bz2 $tar xvf ./vimgdb-for-vim7.3.tar.gz 打patch $patch -p0 < ./vimgdb-for-vim7.3/vim73.patch 编译 $cd ./vim73 $./configure --enable-gdb $make $sudo make install 把./vimgdb-for-vim7.3/vimgdb_runtime/里面的文件拷贝到~/.vim/下推荐使用Pathogen管理plugin，会比较方便一点在~/.vimrc里增加一句 source ~/.vim/macros/gdb_mappings.vim 然后就OK了。编译代码的时候用-gstabs+让gcc把调试的信息加上去。具体请参看vimGBD的文档。这里也行:gdb.txt P.S. 大神们真无聊啊，居然把vim移植到iOS上去了...Vim iOS