C中EOF和''的值是什么 [英] What is value of EOF and '' in C

问题描述

我知道 EOF 和 '' 是整数类型，但如果是这样，它们不应该有一个固定值吗?

I know that EOF and '' are of type integers, but if so shouldn't they have a fixed value?

我打印了两者，EOF 得到 -1，'' 得到 0.但是这些值是固定的吗?

I printed both and got -1 for EOF and 0 for ''. But are these values fixed?

我也有这个

int a=-1;

printf("%d",a==EOF); //printed 1

EOF 和 '' 的值是固定整数吗?

Are the value for EOF and '' fixed integers?

推荐答案

EOF 是一个宏，它扩展为一个整数常量表达式，类型为 int 和一个依赖于实现的负数值但很常见 -1.

EOF is a macro which expands to an integer constant expression with type int and an implementation dependent negative value but is very commonly -1.

'' 是 C++ 中值为 0 的 char 和 C 中值为 0 的 int .

'' is a char with value 0 in C++ and an int with the value 0 in C.

printf("%d",a==EOF); 导致1的原因是你没有赋值EOF 到 a.相反，您检查 a 是否等于 EOF 并且因为这是真的 (a == -1 == EOF) 它打印了 1.

The reason why printf("%d",a==EOF); resulted in 1 was because you didn't assign the value EOF to a. Instead you checked if a was equal to EOF and since that was true (a == -1 == EOF) it printed 1.

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