为什么我的if条件在Java中不接受整数? [英] Why does my if condition not accept an integer in java?
问题描述
当前我正在使用:
int a=10;
if(a=20)
printf("TRUE");
else
printf("false");
在C中打印值 TRUE
.
但是对于Java:
int a=10;
if(a=20)
System.out.println("TRUE");
else
System.out.println("FALSE");
我将收到有关不兼容类型的编译时错误.
I'll get a compile time error about an incompatible type.
推荐答案
原因是在C语言中没有特定的类型 boolean
-相反,任何非0的整数都将计算为boolean真的".因此,在您的C代码中:
The reason for that is that in C there is no specific type boolean
- instead any non-0 integer evaluates to a boolean "true". Thus in your C code:
if(a=20)
为
a
分配了值20,该值非0-并且条件被评估为 true
a
is assigned the value 20, which is non-0 - and the condition is evaluated as true
在Java中,有一个基本类型为 boolean
,并且 if
中的条件值必须为这种类型.
In java, there's a fundamental type boolean
and the value of the conditional inside if
must be of this type.
a=20
Java中的
将20分配给 a
并返回评估的最终结果为整数值20
,但是期望使用 boolean
类型-因此您收到有关不兼容类型的编译时错误.
in Java assigns 20 to a
and returns the final result of evaluation as integer value 20
, however type boolean
is expected - hence you're getting a compile-time error about the incompatible types.
但是,如果要将 a
与20进行比较,则需要在C和Java中都使用 ==
运算符:
If you want to do a comparison of a
with 20, however, you need to use ==
operator both in C and Java:
if(a == 20)
这将使用C和Java进行编译,并以两种语言显示FALSE.
This will compile in both C and Java and print FALSE in both languages.
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