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How to get my IP address programmatically on iOS/macOS?
...un0"
#define IP_ADDR_IPv4 @"ipv4"
#define IP_ADDR_IPv6 @"ipv6"
- (NSString *)getIPAddress:(BOOL)preferIPv4
{
NSArray *searchArray = preferIPv4 ?
@[ /*IOS_VPN @"/" IP_ADDR_IPv4, IOS_VPN @"/" IP_ADDR_IPv6,*/ IOS_WIFI @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6,...
Efficient string concatenation in C++
I heard a few people expressing worries about "+" operator in std::string and various workarounds to speed up concatenation. Are any of these really necessary? If so, what is the best way to concatenate strings in C++?
...
how to convert from int to char*?
...:to_chars(str.data(), str.data() + str.size(), 42);
In C++11, use std::to_string as:
std::string s = std::to_string(number);
char const *pchar = s.c_str(); //use char const* as target type
And in C++03, what you're doing is just fine, except use const as:
char const* pchar = temp_str.c_str(); /...
各编程语言读写文件汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...p);
C#读写文件：
using System.IO;
private void ReadWriteFunc(string str)
{
// 写文件
using (StreamWriter sw = new StreamWriter(@"test.txt"))
{
sw.WriteLine("file content...");
sw.Flush();
sw.Close();
}
// 读文件...
Split value from one field to two
...
Unfortunately MySQL does not feature a split string function. However you can create a user defined function for this, such as the one described in the following article:
MySQL Split String Function by Federico Cargnelutti
With that function:
DELIMITER $$
CREATE ...
printf with std::string?
My understanding is that string is a member of the std namespace, so why does the following occur?
7 Answers
...
Storing Data in MySQL as JSON
...QL 5.7.8, MySQL supports a native JSON type. JSON values are not stored as strings, instead using an internal binary format that permits quick read access to document elements. JSON documents stored in JSON columns are automatically validated whenever they are inserted or updated, with an invalid do...
C++实现一款简单完整的聊天室服务器+客户端 - C/C++ - 清泛网 - 专注C/C++及内核技术
...
MessageBuffer.cpp
//MessageBuffer.cpp
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <pthread.h>
#include "MessageBuffer.h"
MessageBuffer::MessageBuffer() {
toStop = false;
pthread_mutex_init(&mutex,NULL);//初始化互斥量
pthread_cond_init(&condition,NULL)...
What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__?
... in C++11, where it is specified as containing "an implementation-defined string" (C++11 §8.4.1[dcl.fct.def.general]/8), which is not quite as useful as the specification in C. (The original proposal to add __func__ to C++ was N1642).
__FUNCTION__ is a pre-standard extension that some C compilers ...
Does C have a “foreach” loop construct?
... GNU C99.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define FOREACH_COMP(INDEX, ARRAY, ARRAY_TYPE, SIZE) \
__extension__ \
({ \
bool ret = 0; \
if (__builtin_types_compatible_p (const char*, ARRAY_TYPE)) \
ret = INDEX ...