很希望能在hadoop上做c++程序，自己对c++还是有点情节的，根据《hadoop权威指南中文第二版》Hadoop的Pipes进行了试验，并测试成功

#include <algorithm>  
#include <limits.h>  
#include <stdint.h>  
#include <string>  
  
#include "Pipes.hh"  
#include "TemplateFactory.hh"  
#include "StringUtils.hh"  
  
class MaxTemperatureMapper : public HadoopPipes::Mapper {  
public:  
  MaxTemperatureMapper(HadoopPipes::TaskContext& context) {  
  }  
  void map(HadoopPipes::MapContext& context) {  
    std::string line = context.getInputValue();  
    std::string year = line.substr(15, 4);  
    std::string airTemperature = line.substr(87, 5);  
    std::string q = line.substr(92, 1);  
    if (airTemperature != "+9999" &&  
        (q == "0" || q == "1" || q == "4" || q == "5" || q == "9")) {  
      context.emit(year, airTemperature);  
    }  
  }  
};  
  
class MapTemperatureReducer : public HadoopPipes::Reducer {  
public:  
  MapTemperatureReducer(HadoopPipes::TaskContext& context) {  
  }  
  void reduce(HadoopPipes::ReduceContext& context) {  
    int maxValue = http://www.mamicode.com/INT_MIN;  >注意：和书上不一样的地方：limit.h头文件
Makefile文件（自己进行了修改）：
.SUFFIXES:.h .c .cpp .o

CC=g++
CPPFLAGS = -m64 
RM = rm
SRCS = max_temperature.cpp
PROGRAM = max_temperature

INC_PATH = -I$(HADOOP_DEV_HOME)/include
LIB_PATH = -L$(HADOOP_DEV_HOME)/lib/native
LIBS = -lhadooppipes -lcrypto -lhadooputils -lpthread

$(PROGRAM):$(SRCS)
	$(CC) $(CPPFLAGS) $(INC_PATH) $< -Wall $(LIB_PATH) $(LIBS)  -g -O2 -o $@

.PHONY:clean
clean:
	$(RM) $(PROGRAM)
	



源数据文件：
0067011990999991950051507004+68750+023550FM-12+038299999V0203301N00671220001CN9999999N9+00001+99999999999  
0043011990999991950051512004+68750+023550FM-12+038299999V0203201N00671220001CN9999999N9+00221+99999999999  
0043011990999991950051518004+68750+023550FM-12+038299999V0203201N00261220001CN9999999N9-00111+99999999999  
0043012650999991949032412004+62300+010750FM-12+048599999V0202701N00461220001CN0500001N9+01111+99999999999  
0043012650999991949032418004+62300+010750FM-12+048599999V0202701N00461220001CN0500001N9+00781+99999999999
上传到HDFS：hdfs dfs -put sample.txt  
make后生成了可执行文件上传到HDFS： hdfs dfs -put max_temperature /bin

执行方法： hadoop pipes -D hadoop.pipes.java.recordreader=true -D hadoop.pipes.java.recordwriter=true -input /user/root/sample.txt -output /output -program /bin/max_temperature
数据输出结果：


hadoop下c++程序-天气实例