为什么我可以使用'static'限定符声明一个没有类型的变量？ （在C中）

Question

While studying static qualifier in C , I wrote the following code by mistake. I thought that getEven() function would not be compiled but it works well. why can i declare a variable without type?

I tried some test and found that the type of static variable without type is 4 byte integer.

//This code works well.
int getEven(int i) {
static int counter = 0;
if (i%2==0) {
    counter++;
}
    return counter;
}

//I thought this code would make compile error, but it also works well.
int getEven_(int i) {
static counter = 0; //No type!
if (i % 2 == 0) {
    counter++;
}
    return counter;
}

Answer 1

A variable declared without an explicit type name is assumed to be of type int . This rule was revoked in the c99 Standard.

The piece of code will not work if your variable type is char or float.

This is the same reason that you can use unsigned instead of unsigned int , short instead of short int , and static instead of static int . It is better to explicitly qualify variables with int .