C语言 传递参数 1 丢弃来自指针目标类型的限定符
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Passing Argument 1 discards qualifiers from pointer target type
提问by Alex Nichols
My main function is as follows:
我的主要功能如下：
int main(int argc, char const *argv[])
{
huffenc(argv[1]);
return 0;
}
The compiler returns the warning:
编译器返回警告：
huffenc.c:76: warning: passing argument 1 of ‘huffenc' discards qualifiers from pointer target type
huffenc.c:76: warning: passing argument 1 of ‘huffenc' discards qualifiers from pointer target type
For reference, huffenctakes a char*input, and the function is executed, with the sample input "senselessness" via ./huffenc senselessness
作为参考，huffenc接受一个char*输入，然后执行函数，示例输入“无意义”通过./huffenc senselessness
What could this warning mean?
这个警告意味着什么？
回答by Ed S.
It means that you're passing a constargument to a function which takes a non-constargument, which is potentially bad for obvious reasons.
这意味着您将一个const参数传递给一个采用非const参数的函数，由于显而易见的原因，这可能是不好的。
huffencprobably doesn't need a non-constargument, so it should take a const char*. However, your definition of mainis non-standard.
huffenc可能不需要非const参数，所以它应该使用const char*. 但是，您的定义main是非标准的。
The C99 standard Section 5.1.2.2.1 (Program startup) states:
C99 标准第 5.1.2.2.1 节（程序启动）指出：
The function called at program startup is named main. The implementation declares no prototype for this function. It shall be de?ned with a return type of int and with no parameters:
程序启动时调用的函数名为 main。实现声明没有此函数的原型。它应定义为返回类型为 int 且不带参数：
int main(void) { /* ... */ }
or with two parameters (referred to here as argc and argv, though any names may be used, as they are local to the function in which they are declared):
或带有两个参数（此处称为 argc 和 argv，尽管可以使用任何名称，因为它们对于声明它们的函数而言是本地的）：
int main(int argc, char *argv[]) { /* ... */ }
or equivalent;9) or in some other implementation-de?ned manner.
或等价物；9) 或以其他一些实现定义的方式。
And goes on to say...
并继续说...
...The parameters argc and argv and the strings pointed to by the argv array shall be modi?able by the program, and retain their last-stored values between program startup and program termination.
...参数 argc 和 argv 以及 argv 数组指向的字符串应可由程序修改，并在程序启动和程序终止之间保留它们最后存储的值。
