JAVA/C/STL string/thread 数据类型对比

参考网址

https://www.runoob.com/ ==》 各种语言的实用编程实例
https://zh.cppreference.com/ ==》 C/C++ 很全面的参考手册网址

字符串操作

字符串操作包含字符串的构造，查找，连接，拷贝，比较，截取，打印等操作，C++ stl/C库/JAVA 都有相应的函数/类支持

JAVA中使用StringBuilder/StringBuffer/String 类型

示例代码如下：
String 类型一旦确定不能更改，用于固定化字符串
StringBuilder/StringBuffer 用于经常改变字符串内容的场景，和C库函对照表如下：

JAVA 示例代码：

package demoProject;
public class StringDemo {
    public void printString(String str) {
        System.out.println(str);
    }
    private void constructString() {
        String stra = "String Construct a";
        printString(stra);
        String strb = new String("String Construct b");
        printString(strb);
        char[] c = {'A','r','r','a','y'};
        String strc = new String(c);
        printString(strc);
        String strd = new String(c, 0, 3);
        printString(strd);
        String stre = stra.substring(1,10);
        printString(stre);
    }
    
    public void StringOperate() {
        String stra = " String Operate";
        System.out.println("Stra length" + stra.length() + " concat:" + stra.concat(" concate strb"));      
        //trim String 
        System.out.println("Stra substring trim" + stra.trim() +" is Empty:" + stra.isEmpty());
        
        System.out.println("Stra toUpper" + stra.toUpperCase() + " toLowercase" + stra.toLowerCase());
        
        System.out.println("Stra index of O " + stra.indexOf('O'));
        System.out.println("Stra index of Operate " + stra.indexOf("Operate"));
        
        char c = stra.charAt(2);
        System.out.println("charAt(2) is" + c);
    }
    
    private int val = 100;
    private float fval = 3.1415f;
    private boolean bval = true;
    public void FormatString() {
        System.out.printf("Format printf val=%d, fval=%f,bval=%b\n",val,fval,bval);
        String s = String.format("Format String val=%d, fval=%f,bval=%b\n",val,fval,bval);
        System.out.println(s);
    }
    
    
    public void StringDemoOperate() {
        //constructString();
        //StringOperate();  
        FormatString();
        StringOperate();
    }

}

public class StringBufferDemo {
    public void testStringBuilder() {
        StringBuilder sb = new StringBuilder(10);
        sb.append("This is my StringBuilder");
        System.out.println(sb);
    
        //could append all type 
        sb.append("HaHaHa");
        sb.append(false);
        sb.append(10);
        System.out.println(sb);
        
        //insert value 
        sb.insert(5, "InsertValue");
        System.out.println(sb);
        
        //delete value 
        sb.delete(10, 20);
        System.out.println("sb = " + sb + " sb length =" + sb.length());

        //replace value 
        sb.replace(0, sb.length(), "Replaced Content");
        System.out.println("sb = " + sb + " sb length =" + sb.length());
    }
    
    public void testStringBuffer() {
        StringBuffer sbuffer = new StringBuffer();
        sbuffer.append("This is my sBuffer");
        System.out.println("sbuffer = " + sbuffer);
        
        sbuffer.insert(0, "Insert value");
        System.out.println("sbuffer = " + sbuffer);
        
        sbuffer.delete(0, 5);
        System.out.println("sbuffer = " + sbuffer);
        
        sbuffer.replace(5, 10, "HHHHH");
        System.out.println("sbuffer = " + sbuffer); 
    }
}

public class ScannerDemo {
    //next cannot get blank space
    public void testNextMethod() {
        Scanner scan = new Scanner(System.in);
        System.out.println("Next received");
        
        if(scan.hasNext()) {
            String str = scan.next();
            System.out.println("get next string =  " + str);
        }
        
        scan.close();
    }
    
    //next can get blank space
    public void testNextLineMethod() {
        Scanner scan = new Scanner(System.in);
        System.out.println("nextLine received");
        
        if(scan.hasNextLine()) {
            String str = scan.nextLine();
            System.out.println("get next string =  " + str);
        }
        
        scan.close();
    }
}

C库函数中的字符串操作函数

C++ STL 中使用 std::string stringstream类型

参考网址： https://zh.cppreference.com/w/cpp/string/basic_string

示例代码：

#include "stringDemo.h"
#include <iostream>

void stringDemo::printString(const string& str) {
    cout << "print String = " << str << endl;
}

stringDemo::stringDemo() :mstr("Initilize value"){
    printString(mstr);
    string stra = mstr.append("append value");
    printString(stra);
    //strb as ==== constuct from char
    string strb(4, '=');
    printString(strb);
    //construct from stra 0~7 character
    string strc(stra, 0, 7);
    printString(strc);
    char marray[] = { 'H','e', 'l', 'l', 'o','\0'};
    string strd(marray);
    printString(strd);
    string stre(marray, 0, 4);
    printString(stre);
    string strf({ 'C','O','D','E' });
    printString(strf);
    string strg = stra.substr(0,10);
    printString(strg);

}

stringDemo::~ stringDemo() {
    cout << "explict stringDemo ...." << endl;
}

void stringDemo::StrOperate() {
    string stra = "This is demo string";
    // size / empty 
    cout << "string a size:" << stra.size() << " stra is empty:" << stra.empty() << endl;
    //get element
    cout << "string a element[5] :" << stra[5] << " element[6]=" << stra.at(6) << endl;
}
=============================================================================
stringBufferDemo::stringBufferDemo() {
    mstream << "Hello First line \n";
    mstream << "Hello second line \n";
    string mstr = "this is my string";
    mstream << mstr;
    mstream << 10;
    mstream << 10.0000;
    mstream << 'A';
    cout << mstream.str() << endl;
}

线程相关接口

Linux C 线程操作函数接口

Linux C 示例代码：

/*******************************************************************************
     pthread_cond_init pthread_cond_init(pthread_cond_t *cv, \
const pthread_condattr_t *cattr);
     attr 默认值为0
     一般不接返回值

      pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
      函数将解锁mutex参数指向的互斥锁，并使当前线程阻塞在cv参数指向的条件变量上。

      int pthread_cond_signal(pthread_cond_t *cv);

      int pthread_cond_timedwait(pthread_cond_t *cv, pthread_mutex_t *mp, const structtimespec * abstime);

      int pthread_cond_broadcast(pthread_cond_t *cv);
      会解锁所有的线程

      int pthread_cond_destroy(pthread_cond_t *cv);
         
  * @History 2018-01-15
*******************************************************************************/
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
// use posix therad must use this 
#include <pthread.h>
pthread_t thread_handle[2];

//mutex for thread
static pthread_mutex_t mutex;
static pthread_cond_t  cond = PTHREAD_COND_INITIALIZER; 


void *thread1()
{
   while(1)
   {
     pthread_mutex_lock(&mutex);  
     pthread_cond_wait(&cond, &mutex);
     MI_PRINT("%s is running A\n",__FUNCTION__);
     sleep(2);
     pthread_mutex_unlock(&mutex);
     sleep(1);
   }
   
   pthread_exit("thread1 exit");
}


void *thread2()
{
   MI_U8 ret = 0;
   MI_U8 loop = 0;
    while(1)
    {
     pthread_mutex_lock(&mutex);  
     //ret = pthread_mutex_trylock(&mutex);
     //perror("thread2 ----------\n");
  
     MI_PRINT("%s is running B\n",__FUNCTION__);
     sleep(1);
     if( loop > 10 )
     {
        MI_PRINT("now we send thread signal \n");
        pthread_cond_signal(&cond);
     }

     loop++;
       pthread_mutex_unlock(&mutex);
      sleep(1);
     
    }
    pthread_exit("thread2 exit");
 }

MI_U8 _demo_init(void)
{
   // 默认的属性为 NULL
    pthread_mutex_init(&mutex,NULL);  
    pthread_cond_init(&cond, NULL);
    return 1;

}


int main(int argc,char * argv[])
{
    MI_PRINT(" This is my posix thread demo! \n");    
    MI_U8 eRet = -1;
    void *Ptr= NULL;
    _demo_init();
    memset(thread_handle,0x00,sizeof(pthread_t));

    eRet = pthread_create(&thread_handle[0], NULL, thread1, NULL);
    eRet = pthread_create(&thread_handle[1], NULL, thread2, NULL);
    if(eRet)
        goto FAIL;

     // we use pthread join to get some extra value
    pthread_join(thread_handle[1], &Ptr);
    MI_PRINT("The return message is %s \n", (char *)Ptr);
    pthread_join(thread_handle[0],NULL);
    pthread_mutex_destroy(&mutex);   
    pthread_cond_destroy(&cond);

     return 1;
     
FAIL:
    perror("Thread Creat fail!! please check \n");

    return 0;
}

文件操作

数组/容器 类型