[英]Pointer to first element in array! (C)
I'm new to C.我是 C 的新手。
I know this has been asked in many forms but mine is a little unique...I guess.我知道很多 forms 都问过这个问题,但我的有点独特……我猜。 I have an unsigned short pointer.
我有一个无符号短指针。
6 unsigned short *pt;
7 pt = myArray[0];
The array is declared as such: const unsigned short myArray[1024]
and is an array of hex numbers of the form 0x0000 and so on.数组声明如下:
const unsigned short myArray[1024]
并且是 0x0000 等形式的十六进制数数组。
I try to compile, it throws these errors:我尝试编译,它会抛出这些错误:
myLib.c:7: error: data definition has no type or storage class
myLib.c:7: error: type defaults to 'int' in declaration of 'pt'
myLib.c:7: error: conflicting types for 'pt'
myLib.c:6: note: previous declaration of 'pt' was here
myLib.c:7: error: initialization makes integer from pointer without a cast
any ideas of what's going wrong?关于出了什么问题的任何想法?
Thanks, Phil谢谢,菲尔
My guess (you only show two lines) is that this code appears outside a function.我的猜测(您只显示两行)是此代码出现在 function 之外。 This is a statement:
这是一个声明:
pt = myArray[0];
Statements must go in functions.语句必须在函数中使用 go。 Also, if
myArray
has type unsigned short[]
, then you want to do one of these instead:此外,如果
myArray
的类型为unsigned short[]
,那么您想要执行以下操作之一:
pt = myArray;
pt = &myArray[0]; // same thing
&
is the reference operator. &
是参考运算符。 It returns the memory address of the variable it precedes.它返回它前面的变量的 memory 地址。 Pointers store memory addresses .
指针存储memory 地址。 If you want to "store something in a pointer" you dereference it with the
*
operator.如果您想“将某些内容存储在指针中”,您可以使用
*
运算符取消引用它。 When you do that the computer will look into the memory address your pointer contains, which is suitable for storing your value.当您这样做时,计算机将查看您的指针包含的 memory 地址,该地址适合存储您的值。
char *pc; // pointer to a type char, in this context * means pointer declaration
char letter = 'a'; // a variable and its value
pc = &letter; // get address of letter
// you MUST be sure your pointer "pc" is valid
*pc = 'B'; // change the value at address contained in "pc"
printf("%c\n", letter); // surprise, "letter" is no longer 'a' but 'B'
When you use myArray[0]
you don't get an address but a value, that's why people used &myArray[0]
.当您使用
myArray[0]
时,您得到的不是地址而是值,这就是人们使用&myArray[0]
的原因。
Yeah, you really should include a bit more code so we can see the context.是的,您确实应该包含更多代码,以便我们可以看到上下文。
I don't quite get the error messages, but your code is not correct.我不太了解错误消息,但您的代码不正确。
Try:尝试:
pt = &myArray[0];
Or:或者:
pt = myArray + 0;
Or just:要不就:
pt = myArray;
Instead.反而。
You should not throw away the const qualifier;你不应该扔掉 const 限定符; so the pointer should have a const modifier.
所以指针应该有一个 const 修饰符。
const unsigned short myArray[1024];
const unsigned short * pointer = myArray; // set pointer to first element
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