compilation

问题 I have installed many versions of the JDK: 1.4.2, 1.5 and 1.6 . How do I specify which version of the JDK is used when compiling using Ant? 回答1: Two solutions: Specify the full path in your command: for example /opt/java/jdk16/bin/javac ... on Linux Use the -source and -target arguments of the javac command. This allows you specify the source code level and targeted JRE version Also note: Some Linux distributions can include tools to specify which JDK version to use by default. Using -source

问题 I have searched around to get the answers for these questions. but not much luck. Is it possible to run 32-bit code in a machine with 64-bit processor ? The answer seems to be yes. but there is a debate on performance issues, since 32-bits are left unused on the processor. Now my question is vice-versa, Is it possible to run 64-bit code in a machine with 32-bit processor? from my little understanding, the answer is NO, because the code designed to run on 64-bit will be using 64-process

问题 When trying to compile the latest version of QGIS ( https://github.com/qgis/QGIS ) I end up with the folowing erros on cmake-gui: Traceback (most recent call last): File "/opt/QGIS/cmake/FindPyQt5.py", line 34, in <module> import PyQt5.pyqtconfig ImportError: No module named 'PyQt5.pyqtconfig' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/opt/QGIS/cmake/FindPyQt5.py", line 37, in <module> import PyQt5.QtCore ImportError: /usr

问题 I understood what a compile time constant rule is from Compile-time constants and variables. declared as final have a primitive or String type initialized at the same time as the declaration initialized with constant expression final int x = 5; But I fail to understand why below code doesn't: final int x; x = 5; The only difference is of third point above. How initialization on different line instead of same line makes a difference. 回答1: Case 1 final int x = 5; public static void main(String[

问题 I understood what a compile time constant rule is from Compile-time constants and variables. declared as final have a primitive or String type initialized at the same time as the declaration initialized with constant expression final int x = 5; But I fail to understand why below code doesn't: final int x; x = 5; The only difference is of third point above. How initialization on different line instead of same line makes a difference. 回答1: Case 1 final int x = 5; public static void main(String[

问题 I want to install File::Fetch, which is a core module in Perl 5.12, in my Perl 5.8.9. In general, I want to compile and install future-dated modules in my back-dated Perl because I cannot upgrade my Perl. So I downloaded the module and also its dependencies. It's quite painful following the dependency tree but I'm more concerned about the fact that some of them are core modules. If I install these, my Perl 5.8.9 core will have patches from 5.12. My question is how I can know whether I can

问题 I'm trying to compile a java program using command javac -d build src/*.java -verbose It returns me the following: src\Currency.java:5: package javax.ejb does not exist import javax.ejb.*; ^ src\Currency.java:7: cannot find symbol symbol: class EJBObject public interface Currency extends EJBObject { ^ I'm using jdk1.6.0_35. CLASSPATH contains C:\wls1036_dev\modules\ which contains javax.ejb.jar What could possibly be the problem? 回答1: I faced the same problem . You need to add javaee5.jar to

问题 In my Swift code to handle push notification I have this line: if ( application.applicationState == UIApplicationStateInactive || application.applicationState == UIApplicationStateBackground) { } Which cause the compilation error: Use of unresolved identifier 'UIApplicationStateInactive' Am I missing some import files? Thanks 回答1: Currently your are using the identifiers for Objective-C. You need to use the identifier for swift: UIApplicationState.Inactive // equals UIApplicationStateInactive

问题 Below is a simple test.c code using curl: #include <stdio.h> #include <curl/curl.h> int main(){ return 0; } To compile this code I use: gcc test1.c -lcurl -o test1 For test1.c above compilation is correct. Now I would like to write some code using C++ libs (curlpp) and after that compile it. #include <iostream> #include <curlpp/cURLpp.hpp> #include <curlpp/Easy.hpp> #include <curlpp/Options.hpp> int main(){ return 0; } To compile this code I tried: g++ test2.cpp -lcurl -o test2 But I get this

问题 Below is a simple test.c code using curl: #include <stdio.h> #include <curl/curl.h> int main(){ return 0; } To compile this code I use: gcc test1.c -lcurl -o test1 For test1.c above compilation is correct. Now I would like to write some code using C++ libs (curlpp) and after that compile it. #include <iostream> #include <curlpp/cURLpp.hpp> #include <curlpp/Easy.hpp> #include <curlpp/Options.hpp> int main(){ return 0; } To compile this code I tried: g++ test2.cpp -lcurl -o test2 But I get this