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How do I test if a variable is a number in Bash?
...ion, like so:
re='^[0-9]+$'
if ! [[ $yournumber =~ $re ]] ; then
echo "error: Not a number" >&2; exit 1
fi
If the value is not necessarily an integer, consider amending the regex appropriately; for instance:
^[0-9]+([.][0-9]+)?$
...or, to handle numbers with a sign:
^[+-]?[0-9]+([.]...
Android: Test Push Notification online (Google Cloud Messaging) [closed]
...s, device registration id has been changed mainly due to app re-install
{ "error": "Unavailable" } - Server not available, resend the message
{ "error": "InvalidRegistration" } - Invalid device registration Id
{ "error": "NotRegistered"} - Application was uninstalled from the device
...
Git: can't undo local changes (error: path … is unmerged)
...
Typical error when trying a checkout in the midst of a merge: $ git co path/to/file =result=> error: path 'path/to/file' is unmerged => so, first run: $ git reset path/to/file, and then the git checkout path/to/file should ...
Eclipse : An error occurred while filtering resources
I am building a Spring MVC project, and Eclipse is throwing this error (see screenshot). My pom.xml is:
1 Answer
...
error LNK2019: 无法解析的外部符号 __imp__PlaySoundW@12，该符号在函数 \...
error LNK2019: 无法解析的外部符号 __imp__PlaySoundW@12，该符号在函数 "long __stdcall WndProc(struct HWND__ *,unsigned int,unsigned int,long)" (?WndProc@@YGJPAUHWND__@@IIJ@Z) 中被引用#include <mmsystem.h>#pragma comment(lib, "WINMM.LIB")
#include <mmsystem.h>
#pragma comm...
error C2664: “find_char”: 不能将参数 1 从“const char [14]”转换为“...
error C2664: “find_char”: 不能将参数 1 从“const char [14]”转换为“std::string &出错代码：#include <iostream>#include <string>using std::cout;using std::endl;using std::string; const引用形参举例 非const...出错代码：
#include <iostream>
#include <string>
using...
error C2440: “return”: 无法从“const Screen”转换为“Screen &” - C/...
error C2440: “return”: 无法从“const Screen”转换为“Screen &”转换丢失限定符。出错代码（例子来自c++ primer 4th）：Screen& Screen::display(std::ostream& os) const{ os << contents...转换丢失限定符。
出错代码（例子来自c++ primer 4th）：
Screen...
error C2662: “Screen::move”: 不能将“this”指针从“const Screen”转...
error C2662: “Screen::move”: 不能将“this”指针从“const Screen”转换为“ Screen &” 转换丢失限定符出错代码： 成员函数定义Screen& Screen::move(index r,index c){ index row = r * width; cursor = row + c;...出错代码：
//成员函数定义
Screen& Scr...
/usr/include/c++/4.9/bits/stl_iterator_base_types.h:165:53: error: ‘i...
/usr/include/c++/4.9/bits/stl_iterator_base_types.h:165:53: error: ‘int’ is not a class, struct, or union type先看下面的代码(来自:SO)：#include <iostream>#include <cmath>#include <vector>using namespace std;double distance(int a, in...先看下面的代码(来自: SO)：
#include <i...
error C2280: \'std::mutex::mutex(const std::mutex &)\' : attempting to...
error C2280: 'std::mutex::mutex(const std::mutex &)' : attempting to reference a deleted functionstd::mutex是noncopyable的结构，因此不存在拷贝构造函数，所以这里错误提示引用已经删除的函数。错误示例代码如下：解决方法：将包含std::...std::mutex是nonco...