C语言 c - if + else if + else 在一行中？
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c - if + else if + else in one line?
提问by Cjdcoy
I just got a question idea after having misunderstood a friend's statement.
在误解了朋友的陈述后，我刚刚有了一个问题的想法。
My friend told me: I just taught a colleague how to do a if/else in one line in c.
我的朋友告诉我：我刚刚教了一位同事如何在 c 中的一行中执行 if/else。
Example:
例子：
int i = 0;
i < 0 ? printf("i is below 0") : printf("i is over or equal to 0");
For now, nothing new, it's called a ternary and most people know about that kind of statement BUT I first understood that:
现在，没有什么新鲜事，它被称为三元，大多数人都知道这种说法，但我首先明白：
I just taught a colleague how to do a IF / ELSE IF / ELSE in one line. Since I don't / didn't know that doing such a thing is possible I tried to do something like
我刚刚教过一位同事如何在一行中做一个 IF / ELSE IF / ELSE。因为我不/不知道做这样的事情是可能的，所以我尝试做类似的事情
int i = 0;
i < 0 ? printf("i is below 0") : i == 0 ? printf("i equal 0") : printf("i is over 0");
Is it actually possible to do a if / else if / else "ternary". Or is there a way to do such a thing without having an horrible piece of code?
实际上是否可以执行 if / else if / else “三元”。或者有没有办法在没有可怕的代码的情况下做这样的事情？
回答by Some programmer dude
If you see e.g. this conditional expression referenceyou can see that the format of a "ternary expression" is
如果你看到例如这个条件表达式引用，你可以看到“三元表达式”的格式是
condition ? expression-true : expression-false
condition ? expression-true : expression-false
All three parts of the conditional expressions are, in turn, expressions. That means you can have almost anykind of expression, including nested conditional (ternary) expressions in them.
条件表达式的所有三个部分都是表达式。这意味着您几乎可以拥有任何类型的表达式，包括其中的嵌套条件（三元）表达式。
回答by Superman
This is definitely valid.
这绝对是有效的。
Or you could try something like this -
或者你可以尝试这样的事情 -
printf(i < 0 ? "i is below 0" : i == 0 ? "i equal 0" : "i is over 0");
回答by Basile Starynkevitch
C has both statements and expressions. There are two different kinds of syntactical things. BTW lines don't matter much in C (except for the preprocessor).
C 有语句和表达式。有两种不同的句法事物。BTW 行在 C 中并不重要（预处理器除外）。
Expressions (like f(1,x+y)or even x=y++) are a special kind of statements (the most common one).
表达式（likef(1,x+y)或 even x=y++）是一种特殊的语句（最常见的语句）。
As an extension to C, the GCCcompiler adds statement expressions, beyond what the C11standard (read n1570) defines. Please download then read that n1570repoort.
作为 C 的扩展，GCC编译器添加了语句表达式，超出了C11标准（阅读n1570）定义的内容。请下载然后阅读n1570报告。
ifis for conditional statementsbut the ternary ?:operatoris for expressions (with all three operands being sub-expressions).
if用于条件语句，但三元?:运算符用于表达式（所有三个操作数都是子表达式）。
Some programming languages (notably Lisp, Haskell, Scheme, Ocaml) have only expressions and don't have any statements.
一些编程语言（特别是 Lisp、Haskell、Scheme、Ocaml）只有表达式而没有任何语句。
