standards

问题 I read lot of things about pointer arithmetic and undefined behavior (link, link, link, link, link). It always ends up to the same conclusion: Pointer arithmetic is well defined only on array type and between array[0] and array[array_size+1] (one element past the end is valid with regard to the C standard). My question is: Does it means that when the compiler sees a pointer arithmetic not related to any array (undefined behavior), it could emit what it want (even nothing) ? Or is it more a

问题 The void type in C seems to be strange from various different situations. Sometimes it behaves like a normal object type, such as int or char , and sometimes it just means nothing (as it should). Look at my snippet. First of all, it seems strange that you can declare a void object, meaning you just declare nothing. Then I created an int variable and casted its result to void , discarding it: If an expression of any other type is evaluated as a void expression, its value or designator is

问题 The void type in C seems to be strange from various different situations. Sometimes it behaves like a normal object type, such as int or char , and sometimes it just means nothing (as it should). Look at my snippet. First of all, it seems strange that you can declare a void object, meaning you just declare nothing. Then I created an int variable and casted its result to void , discarding it: If an expression of any other type is evaluated as a void expression, its value or designator is

问题 was the idea of nested functions considered to be useless during the time of developing older c++ standard, because its usage is basically covered by another concept like object-oriented programming; or it wasn't implemented just as a matter of simplification? 回答1: Nested functions - to be useful - need the stack frame of the containing function as context. Look at this: class Foo() { void Tripulate() { int i=0; void Dip() { // ... } int x = 12; for(i=1; i<=3; ++i) { int z= 33; Dip(); // ...

问题 was the idea of nested functions considered to be useless during the time of developing older c++ standard, because its usage is basically covered by another concept like object-oriented programming; or it wasn't implemented just as a matter of simplification? 回答1: Nested functions - to be useful - need the stack frame of the containing function as context. Look at this: class Foo() { void Tripulate() { int i=0; void Dip() { // ... } int x = 12; for(i=1; i<=3; ++i) { int z= 33; Dip(); // ...

问题 was the idea of nested functions considered to be useless during the time of developing older c++ standard, because its usage is basically covered by another concept like object-oriented programming; or it wasn't implemented just as a matter of simplification? 回答1: Nested functions - to be useful - need the stack frame of the containing function as context. Look at this: class Foo() { void Tripulate() { int i=0; void Dip() { // ... } int x = 12; for(i=1; i<=3; ++i) { int z= 33; Dip(); // ...

问题 was the idea of nested functions considered to be useless during the time of developing older c++ standard, because its usage is basically covered by another concept like object-oriented programming; or it wasn't implemented just as a matter of simplification? 回答1: Nested functions - to be useful - need the stack frame of the containing function as context. Look at this: class Foo() { void Tripulate() { int i=0; void Dip() { // ... } int x = 12; for(i=1; i<=3; ++i) { int z= 33; Dip(); // ...

问题 Usually, a submit button works fine without a name attribute. However, there are occasions where there's a need to have two submit buttons for the same form, hence making use of the name attribute to identify which button was clicked on the server side. To clarify I am talking about: <input type="submit" name="foo"> 回答1: Yes, it is entirely acceptable. The specification has explicit rules for how to determine which submit button was successful, which would be useless if you couldn't give the

问题 Usually, a submit button works fine without a name attribute. However, there are occasions where there's a need to have two submit buttons for the same form, hence making use of the name attribute to identify which button was clicked on the server side. To clarify I am talking about: <input type="submit" name="foo"> 回答1: Yes, it is entirely acceptable. The specification has explicit rules for how to determine which submit button was successful, which would be useless if you couldn't give the

问题 Does the x86 standard include Mnemonics or does it just define the opcodes? If it does not include them, is there another standard for the different assemblers? 回答1: Mnemonics are not standardised and different assemblers use different mnemonics. Some examples: AT&T-style assemblers apply b , w , l , and q suffixes to all mnemonics to indicate operand size. Intel-style assemblers typically indicate this with the keywords byte , word , dword , and qword AT&T-style assemblers recognise cbtw ,