通过参数引用更新C中的全局变量 [英] Update global variable in C via reference by parameter

问题描述

short int PC = 0;

int main() {
    foo(&PC) ;
}

void foo(short int PC) {
    PC++;
}

如何成功更新PC的全局变量?

How do I successfully update the global variable of PC?

注意:必须将PC作为参数传递，并且需要通过该参数修改全局变量.

Note: PC must be passed as a parameter and the global variable needs to be modified via the parameter.

您可以告诉我，我是C语言的新手，并试图了解 * 和& 之间的区别.任何帮助将不胜感激.

As you can tell I am new to C and am trying to understand the difference between * and &. Any help would be much appreciated.

推荐答案

您只需要将参数用作指针:

You just need to take the argument as a pointer:

short int PC = 0;

void foo(short int *pc) {
    (*pc)++;
}

int main() {
    foo(&PC) ;
}

我将 foo()移到了 main()上方，因为在C语言中，您必须先声明事物，然后再使用它们.如果您愿意，可以通过在顶部说 void foo(); 来声明它，并在下面保留定义.

I moved foo() above main() because in C you have to declare things before they are used. If you prefer you could forward declare it by saying void foo(); at the top and leave the definition below.

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