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assigning 128 to char variable in c

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问题 The output comes to be the 32-bit 2's complement of 128 that is 4294967168. How? #include <stdio.h> int main() { char a; a=128; if(a==-128) { printf("%u\n",a); } return 0; } 回答1: Compiling your code with warnings turned on gives: warning: overflow in conversion from 'int' to 'char' changes value from '128' to '-128' [-Woverflow] which tell you that the assignment a=128; isn't well defined on your plat form. The standard say: 6.3.1.3 Signed and unsigned integers 1 When a value with integer

Self Signed Applet Can it access Local File Systems

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问题 Hi I have created a Self Signed Applet , but not able to access local files system .What have i to do ? 回答1: you need to wrap your IO code inside PrivilegedAction. Generally, you need to sign your applet with your test certificate, the user will see a warning and will have to accept the certificate when it loads the applet. then you need to wrap your code inside a PriviligedAction. see this for some examples. 回答2: The below code is use to Add a Bouncy Castle Jar, the same way you can use it

Signed applet loads signed jar-files using URLClassLoader with security issue

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I have a signed applet. To implement some plugin architecture I download and store to disk a JAR file with specific classes. Then I load these classes with URLCLassLoader . So, now I try to invoke some method from loaded class and I have a security issue. It seems to "sign-token" cannot be checked by SecurityManager when class loaded be URLClassLoaded . Anybody know how to solve this problem? Thanks a lot! Loading. URLClassLoader loader = new URLClassLoader(new URL[] {libraryArchive.toURI().toURL()}, Compress.class.getClassLoader()); Invocation. ... org.palettelabs.comm.desktopcapture.pim

Trying to get a signed applet to work in a browser but fails miserably

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I created a JApplet which uses two external libraries ( JENA and JUNG ). The applet works correctly when i run it from the IDE (using eclipse). I created a jar file, signed it (since the applet needs to read text from disk), created an HTML page to hold the applet, however when i try to run it in a web browser i get the java security warning dialog and when i press run the whole browser tab seems to hang. Here is the HTML file i wrote: <html> <head> <title>Ontology Application</title> </head> <body> <applet code="assignment.Launcher.class" width="1000" height="800" archive="test.jar"></applet>

How can I avoid gcc warning for plain “char” to : “unsigned char” OR “signed char” conversion?

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问题 My default char type is "unsigned char" as set in the gcc option (-funsigned-char gcc). So arguably I can use "char" when I need "unsigned char" in the code. But i am getting warning for conversion between (char*) and (unsigned char* or signed char*): "error: pointer targets in passing argument 1 of 'test2' differ in signedness" . How can I avoid warning when I pass unsigned char* variable to char* (knowing that my syetem has default unsigned char as set by compiler option)? static void test2

Signed applet loads signed jar-files using URLClassLoader with security issue

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问题 I have a signed applet. To implement some plugin architecture I download and store to disk a JAR file with specific classes. Then I load these classes with URLCLassLoader . So, now I try to invoke some method from loaded class and I have a security issue. It seems to "sign-token" cannot be checked by SecurityManager when class loaded be URLClassLoaded . Anybody know how to solve this problem? Thanks a lot! Loading. URLClassLoader loader = new URLClassLoader(new URL[] {libraryArchive.toURI()

Trying to get a signed applet to work in a browser but fails miserably

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问题 I created a JApplet which uses two external libraries (JENA and JUNG). The applet works correctly when i run it from the IDE (using eclipse). I created a jar file, signed it (since the applet needs to read text from disk), created an HTML page to hold the applet, however when i try to run it in a web browser i get the java security warning dialog and when i press run the whole browser tab seems to hang. Here is the HTML file i wrote: <html> <head> <title>Ontology Application</title> </head>

How to trust a certificate in Windows Powershell

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问题 I am using Windows 7 , and want to run signed scripts from Powershell , the security-settings of Powershell are set to "all-signed" , and my scripts are signed with a valid certificate from my company. I have also added the .pfx-file to my local certificate store (right-clicked the pfx-file and installed) . However, when I start a signed script, I get a message that says: "Do you want to run software from this untrusted publisher? File Z:\Powershell Signed Scripts\signed.ps1 is published by

Why stores 255 in a char variable give its value -1 in C?

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I am reading a C book, and there is a text the author mentioned: " if ch (a char variable) is a signed type, then storing 255 in the ch variable gives it the value -1 ". Can anyone elaborate on that? Assuming 8-bit char s, that is actually implementation-defined behaviour. The value 255 cannot be represented as a signed 8-bit integer. However, most implementations simply store the bit-pattern, which for 255 is 0xFF . With a two's-complement interpretation, as a signed 8-bit integer, that is the bit-pattern of -1 . On a rarer ones'-complement architecture, that would be the bit pattern of

How do I efficiently do signed comparisons on the 8080?

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I want to compare two 16-bit numbers and branch on the result: the equivalent of if (a<b) goto negative . I'm using an Intel 8080. The Z80 has a signed arithmetic overflow flag which can be used for this with some degree of effort. The standard code is: ld de, _left ld hl, _right ld a, e sub a, l ld a, d sbc a, h jp po, $+5 ; branch on overflow flag not set xor a, 0x80 ; flip sign bit jm negative ; actually do the test But the 8080 isn't a strict subset of the Z80, and the code above won't work there --- on the 8080, arithmetic instructions set the P flag based on the parity of the result,