更新map中已存在的value值

原因：本来想直接通过插入更新同一key对应的value发现覆盖不了。

实现：

#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include <map>using namespace std;static pthread_mutex_t  mtxBckLoadProgress = PTHREAD_MUTEX_INITIALIZER;typedef std::map<int,float> mapBackupprogress;   //存放备份进度消息
mapBackupprogress rdMapbckupProgress;void AddrecordBckProgress(int backupid, float progress)
{pthread_mutex_lock(&mtxBckLoadProgress);printf("backupid: %d, progress: %f.\n",backupid ,progress);map< int ,float >::iterator it = rdMapbckupProgress.find( backupid );if (it != rdMapbckupProgress.end()){/*,如果map里面插入之前的<key, value>,如果key在map里面有的话，不会覆盖之前的value,一般先判断之前有没有数据，有的话先删除，然后再去添加*/rdMapbckupProgress.erase(it);rdMapbckupProgress.insert(std::make_pair( backupid, progress));printf("[AddrecordBckProgress]:Already Find backupid: %d progress:%f update from map.\n",backupid,progress);}else{rdMapbckupProgress.insert(std::make_pair( backupid, progress));//如果map不存在插入新的printf( "[AddrecordBckProgress]:instert new bckupProgress backupid: %d, progress: %f.\n", it->first, it->second);}it = rdMapbckupProgress.begin();for(;it != rdMapbckupProgress.end();it++){printf("[AddrecordBckProgress]:finally bckupProgress!!! backupid: %d, progress: %f.\n", it->first, it->second);}pthread_mutex_unlock(&mtxBckLoadProgress);return ;
}int recordGetBackuploadprogress(int inkey)
{int ret = -1;//Json::Value root;//AutoMutexLck lck(&mtxBckLoadProgress); // 如不是嵌套锁,请注意锁死问题pthread_mutex_lock(&mtxBckLoadProgress);map< int ,float >::iterator it = rdMapbckupProgress.find( inkey );if (it != rdMapbckupProgress.end()){//root["backupid"]       = it->first;//root["progress"]       = it->second;//result = root.toStyledString().c_str();printf( "[recordGetBackuploadprogress]:recordGetBackuploadprogress backupid: %d, progress: %f.\n", it->first, it->second);ret = 0;}else{printf("[recordGetBackuploadprogress]:Find backupid: %d progress fialed from map.\n",inkey);}pthread_mutex_unlock(&mtxBckLoadProgress);return ret;
}int main()
{float count = 1.03;while(1){AddrecordBckProgress(1,count);count++;sleep(1);if(count >= 10)break;}recordGetBackuploadprogress(1);printf("main exit....\n");return 0;
}

运行结果

huqin@ubuntu:~/Demo$ g++ map.cpp -o map
huqin@ubuntu:~/Demo$ ./map
backupid: 1, progress: 1.030000.
[AddrecordBckProgress]:instert new bckupProgress backupid: 1, progress: 0.000000.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 1.030000.
backupid: 1, progress: 2.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:2.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 2.030000.
backupid: 1, progress: 3.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:3.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 3.030000.
backupid: 1, progress: 4.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:4.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 4.030000.
backupid: 1, progress: 5.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:5.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 5.030000.
backupid: 1, progress: 6.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:6.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 6.030000.
backupid: 1, progress: 7.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:7.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 7.030000.
backupid: 1, progress: 8.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:8.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 8.030000.
backupid: 1, progress: 9.030000.
[AddrecordBckProgress]:Already Find backupid: 1 progress:9.030000 update from map.
[AddrecordBckProgress]:finally bckupProgress!!! backupid: 1, progress: 9.030000.
[recordGetBackuploadprogress]:recordGetBackuploadprogress backupid: 1, progress: 9.030000.
main exit....

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