查看“常用语句 - C++”的源代码

=== 赋值 ===
==== map ====
 <small><nowiki>unordered_map<string, int> um1 = {{"apple", 1}, {"banana", 2}, {"orange", 3}};
// map 相同</nowiki></small>
==== 结构体 ====
 <small><nowiki>struct GVAL {
    int t;    // 0=NULL, 1=int, 2=string
    int i;
    string s;
};
GVAL res1;
res0 = {0};
res1 = {1, 10};
res2 = {2, 0, "ok"};
-.OR.-
res2.t = 2;
res2.s = "ok";

// gcc version 9.4.0</nowiki></small>

==== 数组 ====
 <small><nowiki>char buffer[msg_len + 1] = {0};          // 全部为 \0

memset(buffer, '\0', sizeof(buffer));    // 全部为 \0

P.S. char buffer[msg_len + 1] = {"a"}    // "a", \0, \0...</nowiki></small>

=== 转换 ===
==== 数值转为字符串 ====
 #include <string>
 str1 = to_string(num1);
==== 字符串转换成整数 ====
 #include <string>
 num1 = stoi(str1);

=== 条件 ===
==== map 元素是否存在 ====
 #include <map>
 map<string, int> map1;
 map1["key1"] = 123;
 if (map1.count("key1")) {
     ...
 }

=== 循环 ===
==== map ====
 <nowiki># C++11
for (const auto& pair1 : map1) {
    cout << pair1.first << ": " << pair1.second << endl;
}

# 基本方法：迭代器
for (map<int, string>::iterator it = map1.begin(); it != map1.end(); ++it) {
    cout << it->first << ": " << it->second << endl;
}

# 函数封装
#include <algorithm>
void printPair(const pair<int, string>& p) {
    cout << p.first << ": " << p.second << endl;
}
...
for_each(map1.begin(), map1.end(), printPair);</nowiki>

=== chrono ===
==== 延时函数 ====
 // 线程休眠 200 毫秒
 std::this_thread::sleep_for(std::chrono::milliseconds(200))

usleep 问题
* 在一些平台下不是线程安全，如 HP-UX 以及 Linux
* usleep 影响信号

=== Compile ===
==== 当前函数名 ====
在大多数编译器中，__FUNCTION__ 宏会被替换为当前函数名
 cout << "Current Function: " << __FUNCTION__ << endl;
* __FUNCTION__        : myfun
* __func__            : myfun
* __PRETTY_FUNCTION__ : void sys_info(string), gcc




[[分类:Develop]]
[[分类:C++]]