小编Car*_*low的帖子

如何连接两个字符串流？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include "types.h"    

int main () {
    char dest[1020] = "you";
    char source[7] = "baby";
    stringstream a,b;
    a << source;
    b << dest;
    a << b; /*HERE NEED CONCATENATE*/
    cout << a << endl;
    cout << a.str() << endl;
    return 0;
}

两次尝试中的输出如下:

0xbf8cfd20
baby0xbf8cfddc

期望的输出是babyyou.

我如何打印一个char数组,如初始化,然后连接到另一个char数组？请参阅下面的代码

int main () {
char dest[1020];
char source[7]="baby";
cout <<"source: " <<source <<endl;
cout <<"return value: "<<strcat(dest, source) <<endl;
cout << "pointer pass: "<<dest <<endl;
return 0;
}

这是输出

source: baby
return value: v????baby
pointer pass: v????baby

基本上我想看看输出打印

source: baby
return value: baby
pointer pass: baby

我试图在其初始化的不同函数中获取sizeof char数组变量但是无法获得正确的sizeof.请看下面的代码

int foo(uint8 *buffer){
cout <<"sizeof: "<< sizeof(buffer) <<endl;
}
int main()
{
uint8 txbuffer[13]={0};
uint8 uibuffer[4] = "abc";
uint8 rxbuffer[4] = "def";
uint8 l[2]="g";
int index = 1;

foo(txbuffer);
cout <<"sizeof after foo(): " <<sizeof(txbuffer) <<endl;
return 0;
}

输出是:

sizeof: 4
sizeof after foo(): 13

期望的输出是:

sizeof: 13
sizeof after foo(): 13

如何使用jQuery的数据属性获取输入值？这是我的功能无法正常工作.valuefromcenariotwo的返回值应该是"我的测试2"

var valuefromscenariotwo = getvaluefromScenariotwo("scenario2");
function getvaluefromScenariotwo(name){
  return $(input[data-scenario=name]).val();
}

<div class="form-group">
<input type="text" data-scenario="scenario1" class="form-control notes" placeholder="Enter Notes"           value="My test 1">
</div>;
<div class="form-group">
<input type="text" data-scenario="scenario2" class="form-control notes" placeholder="Enter Notes"   value="My test 2">
</div>;
<div class="form-group">
<input type="text" data-scenario="scenario3" class="form-control notes" placeholder="Enter Notes"   value="My test 3">
</div>;

如何通过引用c ++传递struct参数,请参见下面的代码.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>

using namespace std;
struct TEST
{
  char arr[20];
  int var;
};

void foo(char * arr){
 arr = "baby"; /* here need to set the test.char = "baby" */
}

int main () {
TEST test;
/* here need to pass specific struct parameters, not the entire struct */
foo(test.arr);
cout << test.arr <<endl;
}

所需的输出应该是宝贝.

基本上,我创建了一个地图来存储一个唯一的键和一个项目列表.起初地图是null所以在我的类dosomething我检查地图是否为null但它返回一个异常.请参阅下面的代码.有谁知道我能做些什么来解决这个问题？

public class MyClass{
 private static Map<String, List<MyList>> MyMap = null;
 private static void doSomething(){
  String myKey = "hello";
  if(MyMap.get(myKey) == null ){ // Here is where i got the exception "java.lang.NullPointerException"
    //do something
  }
 }
}
public class MyList{
// do my List
}