希望这是一个简单的问题：
首先，我想知道是否有人知道如何在Linux上使用x86 NASM语法汇编来获取用户输入。现在，我有：
section .data
greet: db 'Hello!', 0Ah, 'What is your name?', 0Ah ;simple greeting
greetL: equ $-greet ;greet length
colorQ: db 'What is your favorite color?' ;color question
colorL: equ $-colorQ ;colorQ length
suprise1: db 'No way '
suprise1L equ $-suprise1
suprise3: db ' is my favorite color, too!', 0Ah
section .bss
name: resb 20 ;user's name
color: resb 15 ;user's color
section .text
global _start
_start:
greeting:
mov eax, 4
mov ebx, 1
mov ecx, greet
mov edx, greetL
int 80 ;print greet
getname:
mov eax, 3
mov ebx, 0
mov ecx, name
mov edx, 20
int 80 ;get name
askcolor:
;asks the user's favorite color using colorQ
getcolor:
mov eax, 3
mov ebx, 0
mov ecx, name
mov edx, 20
int 80
thesuprise:
mov eax, 4
mov ebx, 1
mov ecx, suprise1
mov edx, suprise1L
int 80
mov eax, 4
mov ebx, 1
mov ecx, name
mov edx, 20
int 80
;write the color
;write the "suprise" 3
mov eax, 1
mov ebx, 0
int 80
所以它的作用是询问名称和颜色，然后说：“没办法 - 名字 - - 颜色 - 也是我最喜欢的颜色。
我需要帮助的是如何在用户输入之后查找上面的“名称”和“颜色”变量有多长。否则，我之间会得到一堆长而讨厌的空间，因为我只知道它们的最大尺寸是我之前宣布的。
感谢您的帮助。
答案 0 :(得分：2)
读取系统调用返回eax寄存器中读取的字节数。如果这个数字是＆lt; 0，有某种读取错误。
答案 1 :(得分：1)
您将在循环中调用read。
最简单的方法，尽管不是最好的方法，一次读取一个字节，寻找LF（字节10）。
答案 2 :(得分：1)
I know this is quite old but for anyone in the future looking at this, there is another way to accomplish what the OP is asking for, with basically 1 line. It may not be ideal, but for something like this, it should work fine. Basically, instead of trying to figure out the length of the word that the user input, lets just assume that theyre going to input something like 'RED' or 'ORANGE', etc.. no fancy colors.. So lets assume that the longest color would be like 8 characters. That being said, we can do the following.
java.lang.NullPointerException
at site.entersite.validateFile(entersite.java:172)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.sun.el.parser.AstValue.invoke(AstValue.java:289)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.validator.MethodExpressionValidator.validate(MethodExpressionValidator.java:106)
at javax.faces.component.UIInput.validateValue(UIInput.java:1164)
at javax.faces.component.UIInput.validate(UIInput.java:982)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1248)
at javax.faces.component.UIInput.processValidators(UIInput.java:712)
at javax.faces.component.UIForm.processValidators(UIForm.java:253)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1258)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1258)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
at java.lang.Thread.run(Thread.java:745)
Again, its not ideal but it does work and in this case, a few extra bytes shouldnt effect it too much.