1.map 常用功能
/****************************************
* File Name: map.cpp
* Author: sky0917
* Created Time: 2014年06月 4日 15:49:14
****************************************/
#include <map>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;int main(){
/*
* map::insert 的使用
*/
map<string, int> word_count;word_count.insert(map<string, int>::value_type("zhouzhou",1));
cout<<word_count["zhouzhou"]<<endl;pair<string, int> p("zz",2);
word_count.insert(p);
cout<<word_count["zz"]<<endl;word_count.insert(make_pair("zz", 1));
cout<<p.first<<" "<<p.second<<endl;
word_count["ww"] = 0;pair<map<string, int>::iterator, bool> res = word_count.insert(make_pair("zz",8));
cout<<++res.first->second<<endl;word_count["tt"] = 7;
cout<<"start"<<endl;
for (map<string, int>::iterator it = word_count.begin(); it != word_count.end(); ++it){
cout<<(*it).first<<" "<<(*it).second<<endl;
}
cout<<"end"<<endl;
cout<<"size = " << word_count.size()<<"----"<<endl;
/*
* 查找并读取 map 中的元素
*/int tmp = word_count["sss"];
tmp = word_count["2sdf"]; // 这种查找方式的缺点在于如果该元素不存在，则会插入一个具有该键值的新元素
word_count["zz"] = 9;
if (word_count.count("zz")){
int cont = word_count["zz"];
}
map<string, int>::iterator iot = word_count.find("zz");if (iot != word_count.end())
cout<<(*iot).first<<" "<<(*iot).second<<endl;/*
* 从 map 中删除元素
*/
word_count["bbz"] = 44;
cout<<word_count["bbz"]<<" "<<endl;
cout<<"size = "<< word_count.size()<<endl;
word_count.erase("bbz");
cout<<"size = "<< word_count.size()<<endl;return 0;
}
2. map 示例：
/****************************************
* File Name: map_test.cpp
* Author: sky0917
* Created Time: 2014年06月 4日 17:27:34
****************************************/
#include <map>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <sstream>
#include <iostream>
#include <algorithm>using namespace std;
ifstream& open_file(ifstream &in, const string &file)
{
in.close(); // colse in case it was already open
in.clear(); // clear any existing errors
// if open fails, the stream will be in an invalid state
in.open(file.c_str()); // open
return in;
}
int main(int argc, char **argv){
map<string, string> trm;
string key , value;
if (argc != 3){
puts("wrong number of arguments");
exit(0);
}
ifstream mfile;
if (!open_file(mfile, argv[1])){
puts("cann‘t open the first file");
exit(0);
}
while (mfile >> key >> value){
cout<<"key = " << key <<"value = "<<value<<endl;
trm.insert(make_pair(key, value));
}ifstream input;
if (!open_file(input, argv[2])){
puts("cann‘t open the last file");
exit(0);
}
string line;
while (getline(input, line)){
istringstream stream(line); // read the line a word at a time
string word;
bool firstword = true;
while (stream >> word){
map<string, string>::const_iterator it = trm.find(word);
if (it != trm.end())
word = it->second;
if (firstword)
firstword = false;
else
cout<<" ";
cout<<word;
}
cout<<endl;
}
return 0;
}
map 学习笔记